Cassette system integrated apparatus

ABSTRACT

A cassette integrated system. The cassette integrated system includes a mixing cassette, a balancing cassette, a middle cassette fluidly connected to the mixing cassette and the balancing cassette and at least one pod. The mixing cassette is fluidly connected to the middle cassette by at least one fluid line and the middle cassette is fluidly connected to the balancing cassette by at least one fluid line. The at least one pod is connected to at least two of the cassettes wherein the pod is located in an area between the cassettes.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.14/666,059, entitled “Cassette System Integrated Apparatus,” by Kevin L.Grant et al., filed Mar. 23, 2015, and issued as U.S. Pat. No.9,951,768, which is a continuation of U.S. patent application Ser. No.13/914,138, entitled “Cassette System Integrated Apparatus,” by Kevin.L. Grant et al., filed on Jun. 10, 2013, and issued on Mar. 24, 2015 asU.S. Pat. No. 8,985,133, which is a continuation of U.S. patentapplication Ser. No. 13/156,282, entitled “Cassette System IntegratedApparatus,” by Kevin L. Grant et al., filed on Jun. 8, 2011, and issuedas U.S. Pat. No. 8,459,292 on Jun. 11, 2013, which is a division of U.S.patent application Ser. No. 11/871,803, entitled “Cassette SystemIntegrated Apparatus” by Kevin L. Grant et al., filed on Oct. 12, 2007,and issued as U.S. Pat. No. 7,967,022 on Jun. 28, 2011, each of which isincorporated herein by reference in its entirety. U.S. patentapplication Ser. No. 11/871,803 claims priority from the following U.S.Provisional Patent Applications, both of which are hereby incorporatedherein by reference in their entireties:

U.S. Provisional Patent Application No. 60/904,024 entitled HemodialysisSystem and Methods filed on Feb. 27, 2007; and

U.S. Provisional Patent Application No. 60/921,314 entitled SensorApparatus filed on Apr. 2, 2007 both of which are hereby incorporated byreference in their entireties.

TECHNICAL FIELD

The present invention relates to a cassette system integrated apparatusfor pumping fluid.

SUMMARY OF THE INVENTION

In accordance with one aspect of the cassette integrated system, thecassette integrated system includes a mixing cassette, a balancingcassette, a middle cassette fluidly connected to the mixing cassette andthe balancing cassette and at least one pod. The mixing cassette isfluidly connected to the middle cassette by at least one fluid line andthe middle cassette is fluidly connected to the balancing cassette by atleast one fluid line. The at least one pod is connected to at least twoof the cassettes wherein the pod is located in an area between thecassettes.

Various embodiments of this aspect of the cassette include one or moreof the following. Where the housing includes a top plate, a midplate anda bottom plate. Where the pod includes a curved rigid chamber wallhaving at least one fluid inlet and at least one fluid outlet. Where themixing cassette, middle cassette and said balancing cassette furtherinclude at least one valve. In some embodiments the value is a membranevalve. Where at least one of the fluid lines connecting the cassettes isa rigid hollow cylindrical structure.

In accordance with one aspect of the cassette integrated system, thecassette integrated system includes a mixing cassette, a middle cassetteand a balancing cassette. The mixing cassette includes a mixing cassettehousing including at least one fluid inlet line and at least one fluidoutlet line. The mixing cassette also includes at least onereciprocating pressure displacement membrane pump fluidly connected tothe housing. The pressure pump pumps at least one fluid from the fluidinlet line to at least one of the fluid outlet line. The mixing cassettealso includes at least one mixing chamber fluidly connected to thehousing. The mixing chamber is fluidly connected to the fluid outletline. The middle cassette includes a housing having at least one fluidport and at least one air vent port, the air vent port vents a fluidsource outside the middle cassette housing. The middle cassette alsoincludes at least one reciprocating pressure displacement membrane pumpfluidly connected to the housing. The pump pumps a fluid. The balancingcassette includes a housing including at least two inlet fluid lines andat least two outlet fluid lines. Also, at least one balancing podfluidly connected to the balancing cassette housing and in fluidconnection with the fluid paths. The balancing pod balances the flow ofa first fluid and the flow of a second fluid such that the volume of thefirst fluid equals the volume of the second fluid. The balancing podincludes a membrane wherein the membrane forms two balancing chambers.The balancing cassette also includes at least one reciprocating pressuredisplacement membrane pump fluidly connected to the balancing cassettehousing. The pressure pump pumps a fluid from the fluid inlet line tothe fluid outlet line. The mixing cassette is fluidly connected to themiddle cassette by at least one fluid line, and the middle cassette isfluidly connected to the balancing pod by at least one fluid line. Thereciprocating pressure displacement membrane pumps, mixing chamber andbalancing pod are connected to the housings such that the reciprocatingpressure displacement membrane pumps, mixing chamber and balancing podare located in areas between the cassettes.

Various embodiments of this aspect of the cassette include one or moreof the following. Where the cassette housings include a top plate, amidplate and a bottom plate. Where the reciprocating pressuredisplacement pump includes a curved rigid chamber wall and a flexiblemembrane attached to the rigid chamber wall. The flexible membrane andthe rigid chamber wall define a pumping chamber. Also in someembodiments, tie balancing pod includes a curved rigid chamber wall anda flexible membrane attached to the rigid chamber wall. The flexiblemembrane and the rigid chamber wall define two balancing chambers. Wherethe mixing chamber includes a curved rigid chamber wall having at leastone fluid inlet and at least one fluid outlet. Where the mixingcassette, middle cassette and the balancing cassette further include atleast one valve. Some embodiments of the valve include where the valveis a membrane valve. Some embodiments include where the membrane valveis a volcano valve.

Some embodiments include where the at least one of the fluid linesconnecting the cassettes is a rigid hollow cylindrical structure. Someembodiments include where at least one of the fluid lines connecting thecassettes contain a check valve within the cylindrical structure. Someembodiments of the system include where the mixing cassette furtherincludes at least one metering membrane pump within the mixing cassettehousing. The mixing chamber fluidly connects to the fluid outlet line.Some embodiments of the system include where the balancing cassettefurther includes at least one metering pump within the housing andfluidly connected to a fluid line. The metering pump pumps apredetermined volume of a fluid such that the fluid bypasses thebalancing chambers and wherein the metering pump is a membrane pump.

In accordance with one aspect of the cassette integrated system, thecassette integrated system includes a mixing cassette, a middle cassetteand a balancing cassette. The mixing cassette includes a mixing cassettehousing including at least one fluid inlet line and at least one fluidoutlet line. Also, at least one reciprocating pressure displacementmembrane pump fluidly connected to the housing. The pressure pump pumpsat least one fluid from the fluid inlet line to at least one of thefluid outlet line. The mixing cassette also includes at least one mixingchamber fluidly connected to the housing. The mixing chamber is fluidlyconnected to the fluid outlet line. A plurality of membrane valves and aplurality of fluid lines are also included. The valves control the flowof fluid in the fluid lines. The mixing cassette also includes at leastone metering membrane pump within the mixing cassette housing. Themixing chamber is fluidly connected to the fluid outlet line.

The middle cassette includes a middle cassette housing having at leastone fluid port and at least one air vent port. The air vent port vents afluid source outside the housing. Also includes are a plurality of fluidlines within the middle cassette housing and a plurality of membranevalves. The valves control the flow of fluid in the fluid. At least onereciprocating pressure displacement membrane pump fluidly connected tothe housing is also included. The pump pumps a fluid.

The balancing cassette includes a balancing cassette housing includingat least one inlet fluid line and at least one outlet fluid line. Aplurality of membrane valves and a plurality of fluid paths are alsoincluded. The valves control the flow of fluid in the fluid paths. Atleast one balancing pod fluidly connected to the balancing cassettehousing and in fluid connection with the fluid paths is also included.The balancing pod balances the flow of a first fluid and the flow of asecond fluid such that the volume of the first fluid equals the volumeof the second fluid. The balancing pod includes a membrane which formstwo balancing chambers. The balancing cassette also includes at leastone reciprocating pressure displacement membrane pump fluidly connectedto the balancing cassette housing. The pressure pump pumps a fluid fromthe fluid inlet line to the fluid outlet line. Also, at least onemetering pump within said housing and fluidly connected to a fluid line,wherein said metering pump is included. The metering pump pumps apredetermined volume of a fluid such that the fluid bypasses thebalancing chambers. The metering pump is a membrane pump.

The mixing cassette is fluidly connected to the middle cassette by atleast one fluid line. Also, the middle cassette is fluidly connected tothe balancing pod by at least one fluid line. The reciprocating pressuredisplacement membrane pumps, mixing chamber and balancing pod areconnected to the housing such that they are located in areas betweensaid cassettes.

Various embodiments of this aspect of the cassette include where atleast one of the fluid lines connecting the cassettes is a rigid hollowcylindrical structure.

These aspects of the invention are not meant to be exclusive and otherfeatures, aspects, and advantages of the present invention will bereadily apparent to those of ordinary skill in the art when read inconjunction with the appended claims and accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features and advantages cf the present invention will bebetter understood by reading the following detailed description, takentogether with the drawings wherein:

FIG. 1A is a sectional view of one embodiment of a pod-pump that isincorporated into embodiments of cassette;

FIG. 1B is a sectional view of an exemplary embodiment of a pod pumpthat is incorporated into embodiments of the cassette;

FIG. 2A is an illustrative sectional view of one embodiment of one typeof pneumatically controlled valve that is incorporated into someembodiments of the cassette;

FIG. 2B is a sectional view of another embodiment of one type ofpneumatically controlled valve that is incorporated into someembodiments of the cassette;

FIG. 2C is a sectional view of another embodiment of one type ofpneumatically controlled valve that is incorporated into someembodiments of the cassette;

FIG. 2D is a sectional view of another embodiment of one type ofpneumatically controlled valve that is incorporated into someembodiments of the cassette;

FIGS. 2E-2F are top and bottom views of embodiments of the valvingmembrane;

FIG. 2G shows pictorial, top and cross sectional views of one embodimentof the valving membrane;

FIG. 3 is a sectional view of a pod pump within a cassette;

FIG. 4 is a sectional view of a pod pump within a cassette having avariable membrane;

FIGS. 4A and 4B are top and section views respectively of a pod pumpwithin a cassette having a dimpled/variable membrane;

FIGS. 4C and 4D are pictorial views of a single ring membrane with avariable surface;

FIGS. 5A-5D are side views of various embodiments of variable membranes;

FIGS. 5E-5H are pictorial views of various embodiments of the meteringpump membrane;

FIGS. 6A and 6B are pictorial views of a double ring membrane with asmooth surface;

FIGS. 6C and 6D are pictorial views of a double ring membrane with adimple surface;

FIGS. 6E and 6F are pictorial views of double ring membranes withvariable surfaces;

FIG. 6G is a cross sectional view of a double ring membrane with avariable surface;

FIG. 7 is a schematic showing a pressure actuation system that may beused to actuate a pod pump;

FIG. 8 is one embodiment of the fluid flow-path schematic of thecassette;

FIG. 9 is an alternate embodiment fluid flow-path schematic for analternate embodiment of the cassette;

FIG. 10 is an isometric front view of the exemplary embodiment of theactuation side of the midplate of the cassette with the valves indicatedcorresponding to FIG. 8;

FIG. 11A is an isometric view, and FIG. 11B is a front view of theexemplary embodiment of the outer top plate of the cassette;

FIG. 11C is an isometric view, and FIG. 11D is a front view of theexemplary embodiment of the inner top plate of the cassette;

FIG. 11E is a side view of the exemplary embodiment of the top plate ofthe cassette;

FIG. 12A is an isometric view, and FIG. 12B is a front view of theexemplary embodiment of the fluid side of the midplate of the cassette;

FIG. 12C is an isometric view, and FIG. 12D is a front view of theexemplary embodiment of the fluid side of the midplate of the cassette;

FIG. 12E is a side view of the exemplary embodiment of the midplate ofthe cassette;

FIG. 13A is an isometric view, and FIG. 13B is a front view of theexemplary embodiment of the inner side of the bottom plate of thecassette;

FIG. 13C is an isometric view, and FIG. 13D is a front view of theexemplary embodiment of the outer side of the bottom plate of thecassette;

FIG. 13E is a side view of the exemplary embodiment of the midplate ofthe cassette;

FIG. 14A is a top view of the assembled exemplary embodiment of thecassette;

FIG. 14B is a bottom view of the assembled exemplary embodiment of thecassette;

FIGS. 14C and 14E are exploded views of the assembled exemplaryembodiment of the cassette;

FIG. 14D is an isometric view of an alternate embodiment of the outertop plate of the cassette;

FIGS. 15A-15C show cross sectional views of the exemplary embodiment ofthe assembled cassette;

FIG. 16A shows an isometric view, and FIG. 16B shows a top view of analternate embodiment of the top plate according to an alternateembodiment of the cassette;

FIGS. 16C and 16D show bottom views of an alternate embodiment of thetop plate according to an alternate embodiments of the cassette;

FIG. 16E shows a side view of the alternate embodiment of the top plate;

FIG. 17A shows an isometric view, and FIG. 17B shows a top view of analternate embodiment of the midplate according to an alternateembodiment of the cassette;

FIG. 17C shows an isometric view, and FIG. 17D shows a bottom view of analternate embodiment of the midplate according to an alternateembodiment of the cassette;

FIG. 17E shows a side view of the alternate embodiment of the midplate;

FIG. 18A shows an isometric view, and FIG. 18B shows a top view of analternate embodiment of the bottom plate according to an alternateembodiment of the cassette;

FIG. 18C shows an isometric view, and FIG. 18D shows a bottom view of analternate embodiment of the bottom according to an alternate embodimentof the cassette;

FIG. 18E shows a side view of the alternate embodiment of the bottomplate;

FIG. 19A is a top view of ff assembled alternate embodiment of thecassette;

FIG. 19B is an exploded view of the assembled alternate embodiment ofthe cassette;

FIG. 19C is an exploded view of the assembled alternate embodiment ofthe cassette;

FIGS. 20A-20B show cross sectional views of the exemplary embodiment ofthe assembled cassette;

FIG. 21 is one embodiment of the fluid flow-path schematic of thecassette;

FIG. 22 is an alternate embodiment the fluid flow-path schematic of thecassette;

FIGS. 23A and 23B are isometric and front views of the exemplaryembodiment of the outer top plate of the exemplary embodiment of thecassette;

FIGS. 23C and 23D are isometric and front view s of the exemplaryembodiment of the inner top plate of the cassette;

FIG. 23E is a side view of the top plate of the exemplary embodiment ofthe cassette;

FIGS. 24A and 24B are isometric and front views of the exemplaryembodiment of the liquid side of the midplate of the cassette;

FIGS. 24C and 24D are isometric and front views of the exemplaryembodiment of the air side of the midplate of the cassette;

FIG. 24E is a side view of the midplate according to the exemplaryembodiment of the cassette;

FIGS. 25A and 25B are isometric and front views of the inner side of thebottom plate according to the exemplary embodiment of the cassette;

FIGS. 25C and 25D are isometric and front views of the exemplaryembodiment of the outer side of the bottom plate of the cassette;

FIG. 25E is a side view of the bottom plate according to the exemplaryembodiment of the cassette;

FIG. 26A is a top view of the assembled exemplary embodiment of thecassette;

FIG. 26B a bottom view of the assembled exemplary embodiment of thecassette;

FIG. 26C is an exploded view of the assembled exemplary embodiment ofthe cassette;

FIG. 26D is an exploded view of the assembled exemplary embodiment ofthe cassette;

FIG. 27 shows a cross sectional view of the exemplary embodiment of theassembled cassette;

FIGS. 28A and 28B are isometric and front views of an alternateembodiment of the outer top plate of the cassette;

FIGS. 28C and 28D are isometric and front views of an alternateembodiment of the outer top plate of the cassette;

FIG. 28E is a side view of the top plate of an alternate embodiment ofthe cassette;

FIG. 29 is a front view of the top plate gasket according to analternate embodiment of the cassette;

FIGS. 30A and 30B are isometric and front views of an alternateembodiment of the liquid side of the midplate of the cassette;

FIGS. 30C and 30D are isometric and front views of an alternateembodiment of the air side of the midplate of the cassette;

FIG. 30E is a side view of the midplate according of an alternateembodiment cassette;

FIG. 31 is a front view of the bottom plate gasket according to analternate embodiment of the cassette;

FIGS. 32A and 32B are isometric and front views of an alternateembodiment of the inner side of the bottom plate of the cassette;

FIGS. 32C and 32D are isometric and front views of an alternateembodiment of the outer side of the bottom plate of the cassette;

FIG. 32E is a side view of the bottom plate according to an alternateembodiment of the cassette;

FIG. 33A is a top view of the assembled alternate embodiment of thecassette;

FIG. 33B is a bottom view of the assembled alternate embodiment of thecassette;

FIG. 33C is an exploded view of the assembled alternate embodiment ofthe cassette;

FIG. 33D is an exploded view of the assembled alternate embodiment ofthe cassette;

FIGS. 34A-34B show cross sectional views of the assembled alternateembodiment of the cassette;

FIGS. 35A-35B show cross sectional views of one embodiment of the checkvalve; and

FIGS. 35C-35D show pictorial views of one embodiment of the check valve;

FIG. 36 is one embodiment of the fluid flow-path schematic of thecassette;

FIG. 37 is an alternate embodiment of the fluid flow-path schematic ofthe cassette;

FIG. 38A is an isometric bottom view of the exemplary embodiment of themidplate of the exemplary embodiment of the cassette;

FIG. 38B is an isometric top view of the midplate of the exemplaryembodiment of the cassette;

FIG. 38C is an isometric bottom view of the exemplary embodiment of themidplate of the cassette;

FIG. 38D is a side view of the exemplary embodiment of the midplate ofthe cassette;

FIGS. 39A-39B are isometric and top views of the exemplary embodiment ofthe top plate of the exemplary embodiment of the cassette;

FIGS. 39C-39D are isometric views of the exemplary embodiment of the topplate of the exemplary embodiment of the cassette;

FIG. 39E is a side view of the exemplary embodiment of the top plate ofthe cassette;

FIGS. 40A and 41B are isometric bottom views of the exemplary embodimentof bottom plate of the exemplary embodiment of the cassette;

FIGS. 41C and 41D are isometric top views of the exemplary embodiment ofthe bottom plate of the exemplary embodiment of the cassette;

FIG. 41E is a side view of the exemplary embodiment of the bottom plateof the exemplary embodiment of the cassette;

FIG. 42A is a isometric view of the top of the assembled exemplaryembodiment of the cassette;

FIG. 42B is an isometric view of the bottom of the assembled exemplaryembodiment of the cassette;

FIG. 42C is an exploded view of the assembled exemplary embodiment ofthe cassette;

FIG. 42D is an exploded view of the assembled exemplary embodiment ofthe cassette;

FIGS. 43A-43C show cross sectional views of the exemplary embodiment ofthe assembled cassette;

FIGS. 44A-44B show isometric and top views of an alternate embodiment ofthe top plate according to an alternate embodiment of the cassette;

FIGS. 44C-44D show isometric and bottom views of an alternate embodimentof the top plate according to an alternate embodiment of the cassette;

FIG. 44E shows a side view of the alternate embodiment of the top plate;

FIGS. 45A-45B show isometric and top views of an alternate embodiment ofthe midplate according to an alternate embodiment of the cassette;

FIGS. 45C-45D show isometric and bottom views of an alternate embodimentof the midplate according to an alternate embodiment of the cassette;

FIG. 45E shows a side view of the alternate embodiment of the midplate;

FIGS. 46A-46B show isometric and top views of an alternate embodiment ofthe bottom plate according to an alternate embodiment of the cassette;

FIGS. 46C-46D show isometric and bottom views of an alternate embodimentof the bottom plate according to an alternate embodiment of thecassette;

FIG. 46E shows a side view of the alternate embodiment of the bottomplate;

FIG. 47A is an isometric top view of an assembled alternate embodimentof the cassette;

FIG. 47B is an isometric bottom view of an assembled alternateembodiment of the cassette;

FIG. 47C is an exploded view of the assembled alternate embodiment ofthe cassette;

FIG. 47D is an exploded view of the assembled alternate embodiment ofthe cassette;

FIG. 47E shows a cross sectional view of the exemplary embodiment of theassembled cassette;

FIGS. 48A-48B show isometric and top views of an alternate embodiment ofthe top plate according to an alternate embodiment of the cassette;

FIGS. 48C-48D show isometric and bottom views of an alternate embodimentof the top plate according to an alternate embodiment of the cassette;

FIG. 48E shows a side view of the alternate embodiment of the top plate;

FIGS. 49A-49B show isometric and top views of an alternate embodiment ofthe midplate according to an alternate embodiment of the cassette;

FIGS. 49C-49D show isometric and bottom views of an alternate embodimentof the midplate according to an alternate embodiment of the cassette;

FIG. 49E shows a side view of the alternate embodiment of the midplate;

FIGS. 50A-50B show isometric and top views of an alternate embodiment ofthe bottom plate according to an alternate embodiment of the cassette;

FIGS. 50C-50D show isometric and bottom views of an alternate embodimentof the bottom plate according to an alternate embodiment of thecassette;

FIG. 50E shows a side view of the alternate embodiment of the bottomplate;

FIG. 51A is a top view of an assembled alternate embodiment of thecassette;

FIG. 51B is a bottom view of an assembled alternate embodiment of thecassette;

FIG. 51C is an exploded view of the assembled alternate embodiment ofthe cassette;

FIG. 51D is an exploded view of the assembled alternate embodiment ofthe cassette;

FIG. 52A shows a cross sectional view of the exemplary embodiment of theassembled cassette;

FIG. 52B shows a cross sectional view of the exemplary embodiment of theassembled cassette;

FIG. 53A is an exploded view of the exemplary embodiment of the mixingcassette of the cassette system;

FIG. 53B is an exploded view of the exemplary embodiment of the mixingcassette of the cassette system;

FIG. 54A is an exploded view of the exemplary embodiment of the middlecassette of the cassette system;

FIG. 54B is an exploded view of the exemplary embodiment of the middlecassette of the cassette system;

FIG. 55A is an exploded view of the exemplary embodiment of thebalancing cassette of tie cassette system;

FIG. 55B is an exploded view of the exemplary embodiment of thebalancing cassette of the cassette system;

FIG. 56A is a front view of the assembled exemplary embodiment of thecassette system;

FIG. 56B is an isometric view of the assembled exemplary embodiment ofthe cassette system;

FIG. 56C is an isometric vie of the assembled exemplary embodiment ofthe cassette system;

FIG. 56D is an exploded view of the assembled exemplary embodiment ofthe cassette system;

FIG. 56E is an exploded view of the assembled exemplary embodiment ofthe cassette system;

FIG. 57A is an isometric view of an exemplary embodiment of the pod ofthe cassette system;

FIG. 57B is an isometric view of an exemplary embodiment of the pod ofthe cassette system;

FIG. 57C is a side view of an exemplary embodiment of the pod of thecassette system;

FIG. 57D is an isometric view of an exemplary embodiment of one half ofthe pod of the cassette system;

FIG. 57E is an isometric view of an exemplary embodiment of one half ofthe pod of the cassette system;

FIG. 58A is a pictorial view of the exemplary embodiment of the podmembrane of the cassette system;

FIG. 58B is a pictorial view of the exemplary embodiment of the podmembrane of the cassette system;

FIG. 59 is an exploded view of an exemplary embodiment of the pod of thecassette system;

FIG. 60 is an exploded view of one embodiment of a check valve fluidline in the cassette system;

FIG. 61 is an exploded view of one embodiment of a check valve fluidline in the cassette system; and

FIG. 62 is an isometric view of an exemplary embodiment of a fluid linein the cassette system.

DETAILED DESCRIPTION OF SPECIFIC EMBODIMENTS

1. Pumping Cassette

1.1 Cassette

The pumping cassette includes various features, namely, pod pumps, fluidlines and in some embodiment, valves. The cassette embodiments shown anddescribed in this description include exemplary and some alternateembodiments. However, any variety of cassettes having a similarfunctionality contemplated. As well, although the cassette embodimentsdescribed herein are implementations of the fluid schematics as shown inFIGS. 21 and 22, in other embodiments, the cassette may have varyingfluid paths and/or valve placements and/or pod pump placements andnumbers and thus, is still within the scope of the invention.

In the exemplary embodiment, the cassette includes a top plate, amidplate and a bottom plate. There are a variety of embodiments for eachplate. In general, the top plate includes pump chambers and fluid lines,the midplate includes complementary fluid lines, metering pumps andvalves and the bottom plate includes actuation chambers (and in someembodiments, the top plate and the bottom plate include complementaryportions of a balancing chamber).

In general, the membranes are located between the midplate and thebottom plate, however, with respect to balancing chambers, a portion ofa membrane is located between the midplate and the top plate. Someembodiments include where the membrane is attached to the cassette,either overmolded, captured, bonded, press fit, welded in or any otherprocess or method for attachment, however, in the exemplary embodiments,the membranes are separate from the top plate, midplate and bottom plateuntil the plates are assembled.

The cassettes may be constructed of a variety of materials. Generally,in the various embodiment, the materials used are solid and nonflexible. In the preferred embodiment, the plates are constructed ofpolysulfone, but in other embodiments, the cassettes are constructed ofany other solid material and in exemplary embodiment, of anythermoplastic or thermoset.

In the exemplary embodiment, the cassettes are formed by placing themembranes in their correct locations, assembling the plates in order andconnecting the plates. In one embodiment, the plates are connected usinga laser welding technique. However, in other embodiments, the plates maybe glued, mechanically fastened, strapped together, ultrasonicallywelded or any other mode of attaching the plates together.

In practice, the cassette may be used to pump any type of fluid from anysource to any location. The types of fluid include nutritive, nonnutritive, inorganic chemicals, organic chemicals, bodily fluids or anyother type of fluid. Additionally, fluid in some embodiments include agas, thus, in some embodiments, the cassette is used to pump a gas.

The cassette serves to pump and direct the fluid from and to the desiredlocations. In some embodiments, outside pumps pump the fluid into thecassette and the cassette pumps the fluid out. However, in someembodiments, the pod pumps serve to pull the fluid into the cassette andpump the fluid out of the cassette.

As discussed above, depending on the valve locations, control of thefluid paths is imparted. Thus the valves being in different locations oradditional valves are alternate embodiments of this cassette.Additionally, the fluid lines and paths shown in the figures describedabove are more examples of fluid lines and paths. Other embodiments mayhave more, less and/or different fluid paths. In still otherembodiments, valves are not present in the cassette.

The number of pod pumps described above may also vary depending on theembodiment. For example, although the exemplary and alternateembodiments shown and described above include two pod pumps in otherembodiments, the cassette includes one. In still other embodiments, thecassette includes more than two pod pumps. The pod pumps can be singlepumps or work in tandem to provide a more continuous flow. Either orboth may be used in various embodiments of the cassette.

The various fluid inlets and fluid outlets are fluid ports. In practice,depending on the valve arrangement and control, a fluid inlet can be afluid outlet. Thus, the designation of the fluid port as a fluid inletor a fluid outlet is only for description purposes. The variousembodiments have interchangeable fluid ports. The fluid ports areprovided to impart particular fluid paths onto the cassette. These fluidports are not necessarily all used all of the time; instead, the varietyof fluid ports provides flexibility of use of the cassette in practice.

1.2 Exemplary Pressure Pod Pump Embodiments

FIG. 1A is a sectional view of an exemplary pod pump 100 that isincorporated into a fluid control or pump cassette (see also FIGS. 3 and4), in accordance with an exemplary embodiment of the cassette. In thisembodiment, the pod pump is formed from three rigid pieces, namely a“top” plate 106, a midplate 108, and a “bottom” plate 110 (it should benoted that the terms “top” and “bottom” are relative and are used herefor convenience with reference to the orientation shown in FIG. 1A). Thetop and bottom plates 106 and 110 include generally hemispheroidportions that when assembled together define a hemispheroid chamber,which is a pod pump 100.

A membrane 112 separates the central cavity of the pod pump into twochambers. In one embodiment, these chambers are: the pumping chamberthat receives the fluid to be pumped and an actuation chamber forreceiving the control gas that pneumatically actuates the pump. An inlet102 allows fluid to enter the pumping chamber, and an outlet 104 allowsfluid to exit the pumping chamber. The inlet 102 and the outlet 104 maybe formed between midplate 108 and the top plate 106. Pneumatic pressureis provided through a pneumatic port 114 to either force, with positivegas pressure, the membrane 112 against one wall of the pod pump cavityto minimize the pumping chamber's volume, or to draw, with negative gaspressure, the membrane 112 towards the other wall of the pod pump 100cavity to maximize the pumping chamber's volume.

The membrane 112 is provided with a thickened rim 116, which is heldtightly by a protrusion 118 in the midplate 108. Thus, in manufacturing,the membrane 112 can be placed in and held by the groove 108 before thebottom plate 110 is connected (in the exemplary embodiment) to themidplate 108.

Although not shown in FIGS. 1A and 1B, in some embodiments of the podpump, on the fluid side, a groove is present on the chamber wall. Thegrove acts to prevent folds in the membrane from trapping fluid in thechamber when emptying.

Referring first to FIG. 1A a cross sectional view of a reciprocatingpositive-displacement pump 100 in a cassette is shown. The pod pump 100includes a flexible membrane 112 (also referred to as the “pumpdiaphragm” or “membrane”) mounted where the pumping chamber (alsoreferred to as a “liquid chamber” or “liquid pumping chamber”) wall 122and the actuation chamber (also referred to as the “pneumatic chamber”)wall 120 meet. Te membrane 112 effectively divides that interior cavityinto a variable-volume pumping chamber (defined by the rigid interiorsurface of the pumping chamber wall 122 and a surface of the membrane112) and a complementary variable-volume actuation chamber (defined bythe rigid interior surface of the actuation chamber wall 120 and asurface of the membrane 112). The top portion 106 includes a fluid inlet102 and a fluid outlet 104, both of which are in fluid communicationwith the pumping/liquid chamber. The bottom portion 110 includes anactuation or pneumatic interface 114 in fluid communication to with theactuation chamber. As discussed in greater detail below, the membrane112 can be urged to move back and forth within the cavity by alternatelyapplying negative or vent to atmosphere and positive pneumatic pressureat the pneumatic interface 114. As the membrane 112 reciprocates backand forth, the sum of the volumes of the pumping and actuation chambersremains constant.

During typical fluid pumping operations, the application of negative orvent to atmosphere pneumatic pressure to the actuation or pneumaticinterface 114 tends to withdraw the membrane 112 toward the actuationchamber wall 120 so as to expand the pumping/liquid chamber and drawfluid into the pumping chamber through the inlet 102, while theapplication of positive pneumatic pressure tends to push the membrane112 toward the pumping chamber wall 122 so as to collapse the pumpingchamber and expel fluid in the pumping chamber through the outlet 104.During such pumping operations, the interior surfaces of the pumpingchamber 122 and the actuation chamber wall 120 limit movement of themembrane 112 as it reciprocates back and forth. In the embodiment shownin FIG. 1A, the interior surfaces of the pumping chamber wall 122 andthe actuation chamber wall 120 are rigid, smooth, and hemispherical. Inlieu of a rigid actuation chamber wall 120, an alternative rigid limitstructure—for example, a portion of a bezel used for providing pneumaticpressure and/or a set of ribs—may be used to limit the movement of themembrane as the pumping chamber approaches maximum value. Bezels and ribstructures are described generally in U.S. patent application Ser. No.10/697,450 entitled BEZEL ASSEMBLY FOR PNEUMATIC CONTROL filed on Oct.30, 2003 and published as Publication No. US 2005/0095154 (AttorneyDocket No. 1062/D75) and related PCT Application No. PCT/US2004/035952entitled BEZEL ASSEMBLY FOR PNEUMATIC CONTROL filed on Oct. 29, 2004 andpublished as Publication No. WO 2005/044435 (Attorney Docket No.1062/D71WO) both of which are hereby incorporated herein by reference intheir entireties. Thus, the rigid limit structure—such as the rigidactuation chamber wall 120, a bezel, or a set of ribs—defines the shapeof the membrane 112 when the pumping chamber is at its maximum value. Ina preferred embodiment, the membrane 112 (when urged against the rigidlimit structure) and the rigid interior surface of the pumping chamberwall 122 define a spherical pumping chamber volume when the pumpingchamber volume is at a minimum.

Thus, in the embodiment shown in FIG. 1A, movement of the membrane 112is limited by the pumping chamber wall 122 and the actuation chamberwall 120. As long as the positive and vent to atmosphere or negativepressurizations provided through the pneumatic port 114 are strongenough, the membrane 112 will move from a position limited by theactuation chamber wall 120 to a position limited by the pumping chamberwall 122. When the membrane 112 is forced against the actuation chamberwall 120, the membrane and the pumping chamber wall 122 define themaximum volume of the pumping chamber. When the membrane is forcedagainst the pumping chamber wall 122, the pumping chamber is at itsminimum volume.

In an exemplary embodiment, the pumping chamber wall 122 and theactuation chamber wall 120 both have a hemispheroid shape so that thepumping chamber will have a spheroid shape when it is at its maximumvolume. By using a pumping chamber that attains a spheroid shape—andparticularly a spherical shape—at maximum volume, circulating flow maybe attained throughout the pumping chamber. Such shapes accordingly tendto avoid stagnant pockets of fluid in the pumping chamber. As discussedfurther below, the orientations of the inlet 102 and outlet 104 alsotend to have an impact on the flow of fluid through the pumping chamberand in some embodiments, reduce the likelihood of stagnant pockets offluid forming. Additionally, compared to other volumetric shapes, thespherical shape (and spheroid shapes in general) tends to create lessshear and turbulence as the fluid circulates into, through, and out ofthe pumping chamber.

Referring now to FIGS. 3-4, a raised flow path 30 is shown in thepumping chamber. This raised flow path 30 allows for the fluid tocontinue flowing through the pod pumps after the membrane reaches theend of stroke. Thus, the raised flow path 30 minimizes the chances ofthe membrane causing air or fluid to be trapped in the pod pump or themembrane blocking the inlet or outlet of the pod pump which wouldinhibit continuous flow. The raised flow path 30 is shown in theexemplary embodiment having particular dimensions, however, in alternateembodiments, as seen in FIGS. 18A-18E, the raised flow path 30 isnarrower, or in still other embodiments, the raised flow path 30 can beany dimensions as the purpose is to control fluid flow so as to achievea desired flow rate or behavior of the fluid. Thus, the dimensions shownand described here with respect to the raised flow path, the pod pumps,the valves or any other aspect are mere exemplary and alternateembodiments. Other embodiments are readily apparent.

1.3 Exemplary Balancing Pods Embodiment

Referring now to FIG. 1B, an exemplary embodiment of a balancing pod isshown. The balancing pod is constructed similar to the pod pumpdescribed above with respect to FIG. 1A. However, a balancing podincludes two fluid balancing chambers, rather than an actuation chamberand a pumping chamber, and does not include an actuation port.Additionally, each balancing chamber includes an inlet 102 and an outlet104. In the exemplary embodiment, a groove 126 is included on each ofthe balancing chamber walls 120, 122. The groove 126 is described infurther detail below.

The membrane 112 provides a seal between the two chambers. The balancingchambers work to balance the flow of fluid into and out of the chamberssuch that both chambers maintain an equal volume rate flow. Although theinlets 102 and outlets 104 for each chamber are shown to be on the sameside in other embodiments, the inlets 102 and outlets 104 for eachchamber are on different sides. Also, the inlets 102 and outlets 104 canbe on either side, depending on the flow path in which the balancing podis integrated.

In one embodiment of the balancing pod the membrane 112 includes anembodiment similar to the one described below with respect to FIGS.6A-6G. However, in alternate embodiments, the membrane 112 can be overmolded or otherwise constructed such that a double-ring seal is notapplicable.

1.4 Metering Pumps and Fluid Management System

The metering pump can be any pump that is capable of adding any fluid orremoving any fluid. The fluids include but are not limited topharmaceuticals, inorganic compounds or elements, organic compounds orelements, nutraceuticals, nutritional elements or compounds orsolutions, or any other fluid capable of being pumped. In oneembodiment, the metering pump is a membrane pump. In the exemplaryembodiment, the metering pump is a smaller volume pod pump. In theexemplary embodiment the metering pump includes an inlet and an outlet,similar to a larger pod pump (as shown in FIG. 1A for example). However,the inlet and outlet are generally much smaller than a pod pump and, inone exemplary embodiment, includes a volcano valve-like raised ringaround either the inlet or outlet. Metering pumps include a membrane,and various embodiments of a metering pump membrane are shown in FIGS.5E-5H. The metering pump, in some embodiments, pumps a volume of fluidout of the fluid line. Once the fluid is in the pod pump, a referencechamber, located outside the cassette, using the FMS, determines thevolume that has been removed.

Thus, depending on the embodiment, this volume of fluid that has beenremoved will not then flow to the fluid outlet, the balance chambers orto a pod pump. Thus, in some embodiments, the metering pump is used toremove a volume of fluid from a fluid line. In other embodiments, themetering pump is used to remove a volume of fluid to produce otherresults.

FMS may be used to perform certain fluid management system measurements,such as, for example, measuring the volume of subject fluid pumpedthrough the pump chamber during a stroke of the membrane or detectingair in the pumping chamber, e.g., using techniques described in U.S.Pat. Nos. 4,808,161; 4,826,482; 4,976,162; 5,088,515; and 5,350,357,which are hereby incorporated herein by reference in their entireties.

Metering pumps are also used in various embodiments to pump a secondfluid into the fluid line. In some embodiments, the metering pump isused to pump a therapeutic or a compound into a fluid line. Oneembodiment uses the metering pump to pump a volume of compound into amixing chamber in order to constitute a solution. In some of theseembodiments, the metering pumps are configured for FMS volumemeasurement. In other embodiments, the metering pumps are not.

For FMS measurement, a small fixed reference air chamber is locatedoutside of the cassette, for example, in the pneumatic manifold (notshown). A valve isolates the reference chamber and a second pressuresensor. The stroke volume of the metering pump may be precisely computedby charging the reference chamber with air, measuring the pressure, andthen opening the valve to the pumping chamber. The volume of air on thechamber side may be computed based on the fixed volume of the referencechamber and the change in pressure when the reference chamber wasconnected to the pump chamber.

1.5 Valves

The exemplary embodiment of the cassette includes one or more valves.Valves are used to regulate flow by opening and closing fluid lines. Thevalves included in the various embodiments of the cassette include oneor more of the following: volcano valves or smooth valves. In someembodiment of the cassette check valves may be included. Embodiments ofthe volcano valve are shown in FIGS. 2A and 2B, while an embodiment ofthe smooth valve is shown in FIG. 2C. Additionally, FIGS. 3 and 4 showcross sections of one embodiment of a pod pump in a cassette with aninlet and an outlet valve.

Generally speaking, reciprocating positive-displacement pumps of thetypes just described may include, or may be used in conjunction withvarious valves to control fluid flow through the pump. Thus, forexample, the reciprocating positive-displacement pump or the balancingpods may include, or be used in conjunction with, an inlet valve and/oran outlet valve. The valves may be passive or active. In the exemplaryembodiment of the reciprocating positive-displacement pump the membraneis urged back and forth by positive and negative pressurizations, or bypositive and vent to atmosphere pressurizations, of a gas providedthrough the pneumatic port, which connects the actuation chamber to apressure actuation system. The resulting reciprocating action of themembrane pulls fluid into the pumping chamber from the inlet (the outletvalve prevents liquid from being sucked back into the pumping chamberfrom the outlet) and then pushes the fluid out of the pumping chamberthrough the outlet (the inlet valve prevents fluid from being forcedback from the inlet).

In the exemplary embodiments, active valves control the fluid flowthrough the pump(s) and the cassette. The active valves may be actuatedby a controller in such a manner as to direct flow in a desireddirection. Such an arrangement would generally permit the controller tocause flow in either direction through the pod pump. In a typicalsystem, the flow would normally be in a first direction, e.g., from theinlet to the outlet. At certain other times, the flow may be directed inthe opposite direction, e.g., from the outlet to the inlet. Suchreversal of flow may be employed, for example, during priming of thepump, to check for an aberrant line condition (e.g., a line occlusion,blockage, disconnect, or leak) or to clear an aberrant line condition(e.g., to try to dislodge a blockage).

Pneumatic actuation of valves provides pressure control and a naturallimit to the maximum pressure that may be developed in a system. In thecontext of a system, pneumatic actuation has the added benefit ofproviding the opportunity to locate all the solenoid control valves onone side of the system away from the fluid paths.

Referring now to FIGS. 2A and 2B, sectional views of two embodiments ofa volcano valve are shown. The volcano valves are pneumaticallycontrolled valves that may be used in embodiments of the cassette. Amembrane 202, along with the midplate 204, defines a valving chamber206. Pneumatic pressure is provided through a pneumatic port 208 toeither force, with positive gas pressure, the membrane 202 against avalve seat 210 to close the valve, or to draw, with negative gaspressure, or in some embodiments, with vent to atmospheric pressure, themembrane away from the valve seat 210 to open the valve. A control gaschamber 212 is defined by the membrane 202, the top plate 214, and themidplate 204. The midplate 204 has an indentation formed on it, intowhich the membrane 202 is placed so as to form the control gas chamber212 on one side of the membrane 202 and the valving chamber 206 on theother side.

The pneumatic port 208 is defined by a channel formed in the top plate244. By providing pneumatic control of several valves in a cassette,valves can be ganged together so that all the valves ganged together canbe opened or closed at the same time by a single source of pneumaticpressure. Channels formed on the midplate 204, corresponding with fluidpaths along with the bottom plate 216, define the valve inlet 218 andthe valve outlet 220. Holes formed through the midplate 204 providecommunication between the inlet 218 and the valving chamber 206 andbetween the valving chamber 206 and the outlet 220.

The membrane 202 is provided with a thickened rim 222, which fitstightly in a groove 224 in the midplate 204. Thus, the membrane 202 canbe placed in and held by the groove 224 before the top plate 214 isconnected to the midplate 204. Thus, this valve design may impartbenefits in manufacturing. As shown in FIGS. 2B and 2C, the top plate214 may include additional material extending into control gas chamber212 so as to prevent the membrane 202 from being urged too much in adirection away from the groove 224, so as to prevent the membrane'sthickened rim 222 from popping out of the groove 224. The location ofthe pneumatic port 208 with respect to the control gas chamber 212varies in the two embodiments shown in FIGS. 2A and 2B.

FIG. 2C shows an embodiment in which the valving chamber lacks a valveseat feature. Rather, in FIG. 2C, the valve in this embodiment does notinclude any volcano features and thus, the valving chamber 206, i.e.,the fluid side, does not include any raised features and thus is smooth.This embodiment is used in cassettes used to pump fluid sensitive toshearing. FIG. 2D shows an embodiment in which the valving chamber has araised area to aid in the sealing of the valving membrane. Referring nowto FIGS. 2E-2G, various embodiments of the valve membrane are shown.Although some exemplary embodiments have been shown and described, inother embodiments, variations of the valve and valving membrane may beused.

1.6 Exemplary Embodiments of the Pod Membrane

In some embodiments, the membrane has a variable cross-sectionalthickness, as shown in FIG. 4. Thinner, thicker or variable thicknessmembranes may be used to accommodate tie strength, flexural and otherproperties of the chosen membranes materials. Thinner, thicker orvariable membrane wall thickness may also be used to manage the membranethereby encouraging it to flex more easily in some areas than in otherareas, thereby aiding in the management of pumping action and flow ofsubject fluid in the pump chamber. In this embodiment the membrane isshown having its thickest cross-sectional area closest to its center.However in other embodiments having a membrane with a varyingcross-sectional, the thickest and thinnest areas may be in any locationon the membrane. Thus, for example, the thinner cross-section may belocated near the center and the thicker cross-sections located closer tothe perimeter of the membrane. Still other configurations are possible.Referring to FIGS. 5A-5D, one embodiment of a membrane is shown havingvarious surface embodiments, these include smooth (FIG. 5A), rings (FIG.5D), ribs (FIG. 5C), dimples or dots (FIG. 5B) of variable thickness andor geometry located at various locations on the actuation and or pumpingside of the membrane. In one embodiment of the membrane, the membranehas a tangential slope in at least one section, but in otherembodiments, the membrane is completely smooth or substantially smooth.

Referring now to FIGS. 4A, 4C and 4D, an alternate embodiment of themembrane is shown. In this embodiment, the membrane has a dimpled ordotted surface.

The membrane may be made of any flexible material having a desireddurability and compatibility with the subject fluid. The membrane can bemade from any material that may flex in response to fluid, liquid or gaspressure or vacuum applied to the actuation chamber. The membranematerial may also be chosen for particular bio-compatibility,temperature compatibility or compatibility with various subject fluidsthat may be pumped by the membrane or introduced to the chambers tofacilitate movement of the membrane. In the exemplary embodiment, themembrane is made from high elongation silicone. However, in otherembodiments, the membrane is made from any elastomer or rubber,including, but not limited to, silicone urethane, nitrile, EPDM or anyother rubber, elastomer or flexible material.

The shape of the membrane is dependent on multiple variables. Thesevariables include, but are not limited to: the shape of the chamber, thesize of the chamber, the subject fluid characteristics; the volume ofsubject fluid pumped per stroke; and the means or mode of attachment ofthe membrane to the housing. The size of the membrane is dependent onmultiple variables. These variables include, but are not limited to: theshape of the chamber; the size of the chamber; the subject fluidcharacteristics; the volume of subject fluid pumped per stroke; and themeans or mode of attachment of the membrane to the housing. Thus,depending on these or other variables, the shape and size of themembrane may vary in various embodiments.

The membrane can have any thickness. However, in some embodiments, therange of thickness is between 0.002 inches to 0.125 inches. Depending onthe material used for the membrane, the desired thickness may vary. Inone embodiment, high elongation silicone is used in a thickness rangingfrom 0.015 inches to 0.050 inches. However in other embodiments, thethickness may vary.

In the exemplary embodiment, the membrane is pre-formed to include asubstantially dome-shape in at least part of the area of the membrane.One embodiment of the dome-shaped membrane is shown in FIGS. 4E and 4F.Again, the dimensions of the dome may vary based on some or more of thevariables described above. However, in other embodiments, the membranemay not include a pre-formed dome shape.

In the exemplary embodiment, the membrane dome is formed using liquidinjection molding. However, in other embodiments, the dome may be formedby using compression molding. In alternate embodiments, the membrane issubstantially flat. In other embodiments, the dome size, width or heightmay vary.

In various embodiments, the membrane may be held in place by variousmeans and methods. In one embodiment, the membrane is clamped betweenthe portions of the cassette, and in some of these embodiments, the rimof the cassette may include features to grab the membrane. In others ofthis embodiment, the membrane is clamped to the cassette using at leastone bolt or another device. In another embodiment, the membrane isover-molded with a piece of plastic and then the plastic is welded orotherwise attached to the cassette. In another embodiment, the membraneis pinched between the mid plate described with respect to FIGS. 1A and1B and the bottom plate. Although some embodiments for attachment of themembrane to the cassette are described, any method or means forattaching the membrane to the cassette can be used. The membrane, in onealternate embodiment, is attached directly to one portion of thecassette. In some embodiments, the membrane is thicker at the edge,where the membrane is pinched by the plates, than in other areas of themembrane. In some embodiments, this thicker area is a gasket, in someembodiments an O-ring, ring or any other shaped gasket. Referring againto 6A-6D, one embodiment of the membrane is shown with two gaskets 62,64. In some of these embodiments, the gasket(s) 62, 64 provides theattachment point of the membrane to the cassette. In other embodiments,the membrane includes more than two gaskets. Membranes with one gasketare also included in some embodiments (see FIGS. 4A-4D).

In some embodiments of the gasket, the gasket is contiguous with themembrane. However, in other embodiments, the gasket is a separate partof the membrane. In some embodiments, the gasket is made from the samematerial as the membrane. However, in other embodiments, the gasket ismade of a material different from the membrane. In some embodiments, thegasket is formed by over-molding a ring around the membrane. The gasketcan be any shape ring or seal desired so as to complement the pod pumphousing embodiment. In some embodiments, the gasket is a compressiontype gasket.

1.7 Mixing Pods

Some embodiments of the cassette include a mixing pod. A mixing podincludes a chamber for mixing. In some embodiments, the mixing pod is aflexible structure, and in some embodiments, at least a section of themixing pod is a flexible structure. The mixing pod can include a seal,such as an o-ring, or a membrane. The mixing pod can be any shapedesired. In the exemplary embodiment, the mixing pod is similar to a podpump except it does not include a membrane and does not include anactuation port. Some embodiments of this embodiment of the mixing podinclude an o-ring seal to seal the mixing pod chamber. Thus, in theexemplary embodiment, the mixing pod is a spherical hollow pod with afluid inlet and a fluid outlet. As with the pod pumps, the chamber sizecan be any size desired.

2. Pressure Pump Actuation System

FIG. 7 is a schematic showing an embodiment of a pressure actuationsystem that may be used to actuate a pod pump with both positive andnegative pressure, such as the pod pump shown in FIG. 1A. The pressureactuation system is capable of intermittently or alternately providingpositive and negative pressurizations to the gas in the actuationchamber of the pod pump. However, in some embodiments, FIG. 7 does notapply in these embodiments, actuation of the pod pump is accomplished byapplying positive pressure and vent to atmosphere (again, not shown inFIG. 7). The pod pump—including the flexible membrane, the inlet, theoutlet, the pneumatic port, the pumping chamber, the actuation chamber,and possibly including an inlet check valve and an outlet check valve orother valves—is part of a larger disposable system. The pneumaticactuation system—including an actuation-chamber pressure transducer, apositive-supply valve, a negative-supply valve, a positive-pressure gasreservoir, a negative-pressure gas reservoir, apositive-pressure-reservoir pressure transducer, anegative-pressure-reservoir pressure transducer, as well as anelectronic controller including, in some embodiments, a user interfaceconsole (such as a touch-panel screen)—may be part of a base unit.

The positive-pressure reservoir provides to the actuation chamber thepositive pressurization of a control gas to urge the membrane towards aposition where the pumping chamber is at its minimum volume (i.e., theposition where the membrane is against the rigid pumping-chamber wall).The negative-pressure reservoir provides to the actuation chamber thenegative pressurization of the control gas to urge the membrane in theopposite direction, towards a position where the pumping chamber is atits maximum volume (i.e., the position where the membrane is against therigid actuation-chamber wall).

A valving mechanism is used to control fluid communication between eachof these reservoirs and the actuation chamber. As shown in FIG. 7, aseparate valve is used for each of the reservoirs; a positive-supplyvalve controls fluid communication between the positive-pressurereservoir arid the actuation chamber, and a negative-supply valvecontrols fluid communication between the negative-pressure reservoir andthe actuation chamber. These two valves are controlled by thecontroller. Alternatively, a single three-way valve may be used in lieuof the two separate valves. The valves may be binary on-off valves orvariable-restriction valves.

The controller also receives pressure information from the threepressure transducers: an actuation-chamber pressure transducer, apositive-pressure-reservoir pressure transducer, and anegative-pressure-reservoir pressure transducer. As their names suggest,these transducers respectively measure the pressure in the actuationchamber, the positive-pressure reservoir, and the negative-pressurereservoir. The actuation-chamber-pressure transducer is located in abase unit but is in fluid communication with the actuation chamberthrough the pod pump pneumatic port. The controller monitors thepressure in the two reservoirs to ensure they are properly pressurized(either positively or negatively). In one exemplary embodiment, thepositive-pressure reservoir may be maintained at around 750 mmHG, whilethe negative-pressure reservoir may be maintained at around −450 mmHG.

Still referring to FIG. 7, a compressor-type pump or pumps (not shown)may be used to maintain the desired pressures in these reservoirs. Forexample, two independent compressors may be used to respectively servicethe reservoirs. Pressure in the reservoirs may be managed using a simplebang-bang control technique in which the compressor servicing thepositive-pressure reservoir is turned on if the pressure in thereservoir falls below a predetermined threshold and the compressorservicing the negative-pressure reservoir is turned on if the pressurein the reservoir is above a predetermined threshold. The amount ofhysteresis may be the same for both reservoirs or may be different.Tighter control of the pressure in the reservoirs can be achieved byreducing the size of the hysteresis band, although this will generallyresult in higher cycling frequencies of the compressors. If very tightcontrol of the reservoir pressures is required or otherwise desirablefor a particular application, the bang-bang technique could be replacedwith a PID control technique and could use PWM signals on thecompressors.

The pressure provided by the positive-pressure reservoir is preferablystrong enough—under normal conditions—to urge the membrane all the wayagainst the rigid pumping-chamber wall. Similarly, the negative pressure(i.e., the vacuum) provided by the negative-pressure reservoir ispreferably strong enough—under normal conditions—to urge the membraneall the way against the actuation-chamber wall. In a further preferredembodiment, however, these positive and negative pressures provided bythe reservoirs are within safe enough limits that even with either thepositive-supply valve or the negative-supply valve open all the way, thepositive or negative pressure applied against the membrane is not sostrong as to damage the pod pump or create unsafe fluid pressures (e.g.,that may harm a patient receiving pumped blood of other fluid).

It will be appreciated that other types of actuation systems may be usedto move the membrane back and forth instead of the two-reservoirpneumatic actuation system shown in FIG. 7, although a two-reservoirpneumatic actuation system is generally preferred. For example,alternative pneumatic actuation systems may include either a singlepositive-pressure reservoir or a single negative-pressure reservoiralong with a single supply valve and a single tank pressure sensor,particularly in combination with a resilient membrane. Such pneumaticactuation systems may intermittently provide either a positive gaspressure or a negative gas pressure to the actuation chamber of the podpump. In embodiments having a single positive-pressure reservoir, thepump may be operated by intermittently providing positive gas pressureto the actuation chamber, causing the membrane to move toward thepumping chamber wall and expel the contents of the pumping chamber, andreleasing the gas pressure, causing the membrane to return to itsrelaxed position and draw fluid into the pumping chamber. In embodimentshaving a single negative-pres sure reservoir, the pump may be operatedby intermittently providing negative gas pressure to the actuationchamber, causing the membrane to move toward the actuation chamber walland draw fluid into the pumping chamber, and releasing the gas pressure,causing the membrane to return to its relaxed position and expel fluidfrom the pumping chamber.

3. Fluid Handling

As shown and described with respect to FIGS. 2A-2D, a fluid valve in tieexemplary embodiment consists of a small chamber with a flexiblemembrane or membrane across the center dividing the chamber into a fluidhalf and a pneumatic half. The fluid valve, in the exemplary embodiment,has 3 entry/exit ports, two on the fluid half of the chamber and one thepneumatic half of the chamber. The port on the pneumatic half of thechamber can supply either positive pressure or vacuum (or rather thanvacuum, in some embodiments, there is a vent to atmosphere) to thechamber. When a vacuum is applied to the pneumatic portion of thechamber, the membrane is pulled towards the pneumatic side of thechamber, clearing the fluid path and allowing fluid to flow into and outof the fluid side of the chamber. When positive pressure is applied tothe pneumatic portion of the chamber, the membrane is pushed towards thefluid side of the chamber, blocking the fluid path and preventing fluidflow. In the volcano valve embodiment (as shown in FIGS. 2A-2B) on oneof the fluid ports, that port seals off first when closing the valve andthe remainder of any fluid in the valve is expelled through the portwithout the volcano feature. Additionally, in one embodiment of thevalves, shown in FIG. 2D, the raised feature between the two portsallows for the membrane to seal the two ports from each other earlier inthe actuation stroke (i.e., before the membrane seals the portsdirectly).

Referring again to FIG. 7, pressure valves are used to operate the pumpslocated at different points in the flow path. This architecture supportspressure control by using two variable-orifice valves and a pressuresensor at each pump chamber which requires pressure control. In oneembodiment one valve is connected to a high-pressure source and theother valve is connected to a low-pressure sink. A high-speed controlloop monitors the pressure sensor and controls the valve positions tomaintain the necessary pressure in the pump chamber.

Pressure sensors are used to monitor pressure in the pneumatic portionof the chambers themselves. By alternating between positive pressure andvacuum on the pneumatic side of the chamber, the membrane is cycled backand forth across the total chamber volume. With each cycle, fluid isdrawn through the upstream valve of the inlet fluid port when thepneumatics pull a vacuum on the pods. The fluid is then subsequentlyexpelled through the outlet port and the downstream valve when thepneumatics deliver positive pressure to the pods.

In many embodiments pressure pumps consist of a pair of chambers. Whenthe two chambers are run 180 degrees out of phase from one another theflow is essentially continuous.

4. Volume Measurement

These flow rates in the cassette are controlled using pressure pod pumpswhich can detect end-of-stroke. An outer control loop determines thecorrect pressure values to deliver the required flow. Pressure pumps canrun an end of stroke algorithm to detect when each stroke completes.While the membrane is moving, the measured pressure in the chambertracks a desired sinusoidal pressure. When the membrane contacts achamber wall, the pressure becomes constant, no longer tracking thesinusoid. This change in the pressure signal is used to detect when thestroke has ended, i.e., the end-of-stroke.

The pressure pumps have a known volume. Thus, an end of stroke indicatesa known volume of fluid is in the chamber. Thus, using theend-of-stroke, fluid flow may be controlled using rate equating tovolume.

As described above in more detail, FMS may be used to determine thevolume of fluid pumped by the metering pumps. In some embodiments, themetering pump may pump fluid without using the FMS volume measurementsystem, however, in the exemplary embodiments, the FMS volumemeasurement system is used to calculate the exact volume of fluidpumped.

5. Exemplary Embodiment of the Mixing Cassette

The terms inlet and outlet as well as first fluid, second fluid, thirdfluid, and the number designations given to valving paths (i.e. “firstvalving path”) are used for description purposes only. In otherembodiments, an inlet can be an outlet, as well, an indication of afirst, second, third fluid does not denote that they are differentfluids or are in a particular hierarchy. The denotations simply refer toseparate entrance areas into the cassette and the first, second, third,etc., fluids may be different fluids or the same fluid types orcomposition or two or more may be the same. Likewise, the designation ofthe first, second, third, etc. valving paths do not have any particularmeaning, but are used for clearness of description.

The designations given for the fluid inlets (which can also be fluidoutlets), for example, first fluid outlet, second fluid outlet, merelyindicate that a fluid may travel out of or into the cassette via thatinlet/outlet. In some cases, more than one inlet/outlet on the schematicis designated with an identical name. This merely, describes that all ofthe inlet/outlets having that designation are pumped by the samemetering pump or set of pod pumps (which in alternate embodiments, canbe a single pod pump).

Referring now to FIG. 8, an exemplary embodiment of the fluid schematicof the cassette 800 is shown. Other schematics are readily discernable.The cassette 800 includes at least one pod pump 828, 820 and at leastone mixing chamber 818. The cassette 800 also includes a first fluidinlet 810, where a first fluid enters the cassette. The first fluidincludes a flow rate provided by one of the at least one pod pump 820,828 in the cassette 800. The cassette 800 also includes a first fluidoutlet 824 where fluid exits the cassette 800 having a flow rateprovided by one of the at least one pod pump 820, 828. The cassette 800includes at least one metering fluid line 812, 814, 816 that is in fluidconnection with the first fluid outlet. The cassette also includes atleast one second fluid inlet 826 where the second fluid enters thecassette 800. In some embodiments of the cassette 800 a third fluidinlet 825 is also included.

Metering pumps 822, 830 pump the second fluid and the third fluid intothe first fluid outlet line. The second fluid and, in some embodiments,the third fluid, connected to the cassette 800 at the second fluid inlet826 and third fluid inlet 825 respectively, are each fluidly connectedto a metering pump 822, 830 and to the first fluid outlet line through ametering fluid line 812, 814, 816. The metering pumps 822, 830,described in more detail below, in the exemplary embodiment, include avolume measurement capacity such that the volume of fluid pumped by themetering pumps 822, 830 is readily discernable.

The mixing chamber 818 is connected to the first fluid outlet line 824and includes a fluid inlet and a fluid outlet. In some embodiments,sensors are located upstream and downstream from the mixing chamber 818.The location of the sensors in the exemplary embodiment are shown anddescribed below with respect to FIGS. 14C, 14D and FIGS. 15B and 15C.

The cassette 800 is capable of internally mixing a solution made up ofat least two components. The cassette 800 also includes the capabilityof constituting a powder to a fluid prior to pumping the fluid into themixing chamber. These capabilities will be described in greater detailbelow.

Various valves 832-860 impart the various capabilities of the cassette800. The components of the cassette 800 may be used differently in thedifferent embodiments based on various valving controls.

The fluid schematic of the cassette 800 shown in FIG. 8 may be embodiedinto various cassette apparatus. Thus, the embodiments of the cassette800 including the fluid schematic shown in FIG. 8 are not the onlycassette embodiments that may incorporate this or an alternateembodiment of this fluid schematic. Additionally, the types of valves,the ganging of the valves, the number of pumps and chambers may vary invarious cassette embodiments of this fluid schematic.

Referring now to FIG. 8, a fluid flow-path schematic 800 is shown withthe fluid paths indicated based on different valving flow paths. Thefluid flow-path schematic 800 is described herein corresponding to thevalving flow paths in one embodiment of the cassette. The exemplaryembodiment of the midplate 900 of the cassette are shown in FIG. 10 withthe valves indicated corresponding to the respective fluid flow-pathschematic 800 in FIG. 8. For the purposes of the description, the fluidflow paths will be described based on the valving. The term “valvingpath” refers to a fluid path that may, in some embodiments, be availablebased on the control of particular valves. The corresponding fluid sidestructures of FIG. 10 are shown in FIG. 12A.

Referring now to FIGS. 8 and 10 the first valving path includes valves858, 860. This valving path 858, 860 includes the metering fluid line812, which connects to the second fluid inlet 826. As shown in theseFIGS., in some embodiments of the cassette, there are two second fluidinlets 826. In practice, these two second fluid inlets 826 can beconnected to the same fluid source or a different fluid source. Eitherway, the same fluid or a different fluid may be connected to each secondfluid inlet 826. Each second fluid inlet 826 is connected to a differentmetering fluid line 812, 814.

The first of the two metering fluid lines connected to the second fluidinlet 826 is as follows. When valve 858 opens and valve 860 is closedand metering pump 822 is actuated, fluid is drawn from the second fluidinlet 826 and into metering fluid line 812. When valve 860 is open andvalve 858 is closed and the metering pump 822 is actuated, second fluidcontinues on metering fluid line 812 into pod pump 820.

Referring now to the second valving path including valve 842, when valve842 is open and pod pump 820 is actuated, fluid is pumped from pod pump820 to one of the third fluid inlet 825. In one embodiment, this valvingpath is provided to send liquid into a container or source connected tothird fluid inlet 825.

Referring now to the third valving path including valves 832 and 836this valving path 832, 835 includes the metering fluid line 816, whichconnects to the third fluid inlet 825. As shown in these FIGS., in someembodiments of the cassette, there are two third fluid inlets 825. Inpractice, these two third fluid inlets 825 can be connected to the samefluid source or a different fluid source. Either way, the same fluid ora different fluid may be connected to each third fluid inlet 825. Eachthird fluid inlet 825 is connected to a different metering fluid line862, 868.

When valve 832 opens and valve 836 is closed and metering pump 830 isactuated, fluid is drawn from the third fluid inlet 825 and intometering fluid line 830. When valve 836 is open and valve 832 is closedand the metering pump 830 is actuated, third fluid continues on meteringfluid line 816 into first fluid outlet line 824.

Referring now to the fourth valving path, valve 846, when valve 846 isopen and pod pump 820 is actuated, fluid is pumped from pod pump 820 toone of the third fluid inlet 825. In one embodiment, this valving pathis provided to send liquid into a container or source connected to thirdfluid inlet 825.

Referring now to the fifth valving path, when valve 850 opens and podpump 820 is actuated, fluid is pumped into the cassette 800 through thefirst fluid inlet 810, and into pod pump 820.

Referring now to the sixth valving path, when valve 838 is open and podpump 820 is actuated, fluid is pumped from pod pump 820 to the mixingchamber 818 and to the first fluid outlet 824.

The seventh valving path includes valves 858, 856. This valving path858, 856 includes the metering fluid line 812, which connects to thesecond fluid inlet 826. As shown in these FIGS., in some embodiments ofthe cassette, there are two second fluid inlets 826. In practice, thesetwo second fluid inlets 826 can be connected the same fluid source or adifferent fluid source. Either way, the same fluid or a different fluidmay be connected to each second fluid inlet 826. Each second fluid inlet826 is connected to a different metering fluid line 812, 814.

When valve 858 opens and valve 856 is closed and metering pump 822 isactuated, fluid is drawn from the second fluid inlet 826 and intometering fluid line 812. When valve 856 is open and valve 858 is closed,and the metering pump is actuated, second fluid continues on meteringfluid line 814 into pod pump 828.

Referring now to the eighth valving path, valve 848, when valve 848 isopen and pod pump 828 is actuated, fluid is pumped from pod pump 828 toone of the third fluid inlet 825. In one embodiment, this valving pathis provided to send fluid/liquid into a container or source connected tothird fluid inlet 825.

Referring now to the ninth valving path including valve 844, when valve844 is open and pod pump 828 is actuated, fluid is pumped from pod pump828 to one of the third fluid inlet 825. In one embodiment, this valvingpath is provided to send liquid into a container or source connected tothird fluid inlet 825.

Referring now to the tenth valving path, valve 848, when valve 848 isopen and pod pump 828 is actuated, fluid is pumped from pod pump 828 toone of the third fluid inlet 825. In one embodiment, this valving pathis provided to send fluid/liquid into a container or source connected tothird fluid inlet 825.

The eleventh valving path including valves 854 and 856 is shown. Thisvalving path 854, 856 includes the metering fluid line 814, whichconnects to the second fluid inlet 826. As shown in these FIGS., in someembodiments of the cassette, there are two second fluid inlets 826. Inpractice, these two second fluid inlets 826 can be connected the samefluid source or a different fluid source. Either way, the same fluid ora different fluid may be connected to each second fluid inlet 826. Eachsecond fluid inlet 826 is connected to a different metering fluid line812, 814.

The second of the two metering fluid lines connected to the second fluidinlet 826 is shown in FIG. 8. The twelfth valving path is as follows.When valve 854 opens and valve 856 is closed and metering pump 822 isactuated, fluid is drawn from the second fluid inlet 826 and intometering fluid line 814. When valve 856 is open and valve 854 is closedarid the metering pump 822 is actuated, the second fluid continues onmetering fluid line 814 into pod pump 828.

Similarly, the thirteenth valving path is seen when valve 854 opens andvalve 860 is closed and metering pump 822 is actuated, fluid is drawnfrom the second fluid inlet 826 and into metering fluid line 814. Whenvalve 860 is open and valve 854 is closed, and the metering pump 822 isactuated, the second fluid continues on metering fluid line 814 into podpump 820.

Referring now to the fourteenth valving path including valve 852. Whenvalve 852 opens and pod pump 828 is actuated, fluid is pumped into thecassette 800 through the first fluid inlet 810, and into pod pump 828.

Referring now to the fifteenth valving path, when valve 840 is open andpod pump 828 is actuated, fluid is pumped from pod pump 828 to themixing chamber 818 and to the first fluid outlet 824. The sixteenthvalving path including valve 834, when valve 834 is open and valve 836opens, and the metering pump 830 is actuated, fluid from the third fluidinlet 825 flows on metering fluid line 862 and to metering fluid line816.

In the exemplary fluid flow-path embodiment shown in FIG. 8, andcorresponding structure of the cassette shown in FIG. 10, valves areopen individually. In the exemplary embodiment, the valves arepneumatically open. Also, in the exemplary embodiment, the fluid valvesare volcano valves, as described in more detail in this specification.

Referring now to FIGS. 11A-11D, the top plate 1100 of exemplaryembodiment of the cassette is shown. In the exemplary embodiment, thepod pumps 820, 828 and the mixing chambers 818 on the top plate 1100,are formed in a similar fashion. In the exemplary embodiment, the podpumps 820, 828 and mixing chamber 818, when assembled with the bottomplate, have a total volume of capacity of 38 ml. However, in otherembodiments, the mixing chamber can have any size volume desired.

Referring now to FIGS. 11C and 11D, the bottom view of the top plate1100 is shown. The fluid paths are shown in this view. These fluid pathscorrespond to the fluid paths shown in FIGS. 12A-12D in the midplate1200. The top plate 1100 and the top of the midplate 1200 form theliquid or fluid side of the cassette for the pod pumps 820, 828 and forone side of the mixing chamber 818. Thus, most of the liquid flow pathsare on the top 1100 and midplates 1200. Referring to FIGS. 12C and 12D,the first fluid inlet 810 and the first fluid outlet 824 are shown.

Still referring to FIGS. 11A-11D, the pod pumps 820, 828 include agroove 1002 (in alternate embodiments, this is a groove). The groove1002 is shown having a particular size and shape, however, in otherembodiments, the size and shape of the groove 1002 can be any size orshape desirable. The size and shape shown in FIGS. 11A-11D is theexemplary embodiment. In all embodiments of the groove 1002, the groove1002 forms a path between the fluid inlet side and the fluid outlet sideof the pod pumps 820, 828. In alternate embodiments, the groove 1002 isa groove in the inner pumping chamber wall of the pod pump.

The groove 1002 provides a fluid path whereby when the membrane is atthe end-of-stroke there is still a fluid path between the inlet andoutlet such that the pockets of fluid or air do not get trapped in thepod pump. The groove 1002 is included in both the liquid/fluid andair/actuation sides of the pod pumps 820, 828. In some embodiments, thegroove 1002 may also be included in the mixing chamber 818 (see FIGS.13A-13D with respect to the actuation/air side of the pod pumps 820, 828and the opposite side of the mixing chamber 818. In alternateembodiments, the groove 1002 is either not included or on only one sideof the pod pumps 820, 828.

In an alternate embodiment of the cassette, the liquid/fluid side of thepod pumps 820, 828 may include a feature (not shown) whereby the inletand outlet flow paths are continuous and a rigid outer ring (not shown)is molded about the circumference of the pumping chamber is alsocontinuous. This feature allows for the seal, formed with the membrane(not shown) to be maintained. Referring to FIG. 11E, the side view ofthe exemplary embodiment of the top plate 1100 is shown.

Referring now to FIGS. 12A-12D, the exemplary embodiment of the midplate1200 is shown. The midplate 1200 is also shown in FIGS. 14C and 14E,where these figures correspond with FIGS. 12A-12D. Thus, FIGS. 14C and14E indicate the locations of the various valves and valving paths. InFIGS. 12A-12D, the locations of the membranes (not shown) for therespective pod pumps 820, 828 as well as the location of the mixingchamber 818 are shown.

Referring now to FIG. 12C, in the exemplary embodiment of the cassette,sensor elements are incorporated into the cassette so as to discernvarious properties of the fluid being pumped. In one embodiment, threesensor elements are included. However, in the exemplary embodiment, sixsensor elements (two sets of three) are included. The sensor elementsare located in the sensor cell 1314, 1316. In this embodiment, a sensorcell 1314, 1316 is included as an area on the cassette for sensor(s)elements. In the exemplary embodiment, the three sensor elements of thetwo sensor cells 1314, 1316 are housed in respective sensor elementshousings 1308, 1310, 1312 and 1318, 1320, 1322. In the exemplaryembodiment, two of the sensor elements housings 1308, 1312 and 1318,1320 accommodate a conductivity sensor elements and the third sensorelements housing 1310, 1322 accommodates a temperature sensor elements.The conductivity sensor elements and temperature sensor elements can beany conductivity or temperature sensor elements in the art. In oneembodiment, the conductivity sensors are graphite posts. In otherembodiments, the conductivity sensor elements are posts made fromstainless steel, titanium, platinum or any other metal coated to becorrosion resistant and still be electrically conductive. Theconductivity sensor elements will include an electrical lead thattransmits the probe information to a controller or other device. In oneembodiment, the temperature sensor is a thermister potted in a stainlesssteel probe. However, in alternate embodiments, a combinationtemperature and conductivity sensor elements is used similar to the onedescribed in co-pending U.S. patent application entitled SensorApparatus Systems, Devices and Methods filed Oct. 12, 2007 (U.S.application Ser. No. 11/871,821).

In alternate embodiments, there are either no sensors in the cassette oronly a temperature sensor, only one or more conductivity sensors or oneor more of another type of sensor.

Referring now to FIG. 12E, the side view of the exemplary embodiment ofthe midplate 1200 is shown.

Referring now to FIGS. 13A-13D, the bottom plate 1300 is shown.Referring first to FIGS. 13A and 13B, the inner or inside surface of thebottom plate 1300 is shown. The inner or inside surface is the side thatcontacts the bottom surface of the midplate (not shown, see FIG. 14E).The bottom plate 1300 attaches to the air or actuation lines (notshown). The corresponding entrance holes for the air that actuates thepod pumps 820, 828 and valves (not shown, see FIGS. 14C and 14E) in thebottom plate 1300 can be seen. Holes 810, 824 correspond to the firstfluid inlet and first fluid outlet shown in FIGS. 12C and 12D, 810, 824respectively. The corresponding halves of the pod pumps 820, 828 andmixing chamber 818 are also shown, as are the grooves 1002 for the fluidpaths. The actuation holes in the pumps are also shown. Unlike the topplate, the bottom plate 1300 corresponding halves of the pod pumps 820,828 and mixing chamber 818 make apparent the difference between the podpumps 820, 828 and mixing chamber 818. The pod pumps 820, 828 include anair/actuation path on the bottom plate 1300, while the mixing chamber818 has identical construction to the half in the top plate. The mixingchamber 818 mixes liquid and therefore, does not include a membrane (notshown) nor an air/actuation path. The sensor cell 1314, 1316 with thethree sensor element housings 1308, 1310, 1312 and 1318, 1320, 1322 arealso shown.

Referring now to FIGS. 13C and 13D, the actuation ports 1306 are shownon the outside or outer bottom plate 1300. An actuation source isconnected to these actuation ports 1306. Again, the mixing chamber 818does not have an actuation port as it is not actuated by air. Referringto FIG. 13E, a side view of the exemplary embodiment of the bottom plate1300 is shown.

5.1 Membranes

In the exemplary embodiment, the membrane is a gasket o-ring membrane asshown in FIG. 5A. However, in some embodiments, a gasket o-ringmembranes having texture, including, but not limited to, the variousembodiments in FIG. 4D, or 5B-5D may be used. In still otherembodiments, the membranes shown in FIGS. 6A-6G may also be used.

Referring next to FIGS. 14A and 14B, the assembled exemplary embodimentof the cassette 1400 is shown. FIGS. 14C and 14E are an exploded view ofthe exemplary embodiment of the cassette 1400. The membranes 1600 areshown. As can be seen from FIGS. 14C and 14E, there is one membrane 1602for each of the pods pumps. In the exemplary embodiment, the membranefor the pod pumps is identical. In alternate embodiments, any membranemay be used, and one pod pump could use one embodiment of the membranewhile the second pod pump can use a different embodiment of the membrane(or each pod pump can use the same membrane).

The various embodiments of the membrane used in the metering pumps 1604,in the preferred embodiment, are shown in more detail in FIGS. 5E-5H.The various embodiments of the membrane used in the valves 1222 is shownin more detail in FIGS. 2E-2G. However, in alternate embodiments, themetering pump membrane as well as the valve membranes may containtextures for example, but not limited to, the textures shown on the podpump membranes shown in FIGS. 5A-5D.

One embodiment of the conductivity sensor elements 1314, 1316 and thetemperature sensor element 1310, which make up the sensor cell 1322, arealso shown in FIGS. 14C and 14E. Still referring to FIGS. 14C and 14E,the sensor elements are housed in sensor blocks (shown as 1314, 1316 inFIGS. 12C and 13A and B) which include areas on the bottom plate 1300and the midplate 1200. O-rings seal the sensor housings from the fluidlines located on the upper side of the midplate 1200 and the inner sideof the top plate 1100. However, in other embodiments, an o-ring ismolded into the sensor block or any other method of sealing can be used.

5.2 Cross Sectional Views

Referring now to FIGS. 15A-15C, various cross sectional views of theassembled cassette are shown. Referring first to FIG. 15A, the membranes1602 are shown in a pod pumps 820, 828. As can be seen from the crosssection, the o-ring of the membrane 1602 is sandwiched by the midplate1200 and the bottom plate 1300. A valve membrane 1606 can also be seen.As discussed above, each valve includes a membrane.

Referring now to FIG. 15B, the two conductivity sensors 1308, 1312 andthe temperature sensor 1310 are shown. As can be seen from the crosssection, the sensors 1308, 1310, 1312 are in the fluid line 824. Thus,the sensors 1308, 1310, 1312 are in fluid connection with the fluid lineand can determine sensor data of the fluid exiting fluid outlet one 824.Still referring to FIG. 15B, a valve 836 cross section is shown. Asshown in this figure, in the exemplary embodiment, the valves arevolcano valves similar to the embodiment shown and described above withrespect to FIG. 2B. However, as discussed above, in alternateembodiment, other valves are used including, but not limited, to thosedescribed and shown above with respect to FIGS. 2A, 2C and 2D.

Referring now to FIG. 15C, the two conductivity sensor elements 1318,1320 and the temperature sensor element 1322 are shown. As can be seenfrom the cross section, the sensor elements 1318, 1320, 1322 are in thefluid line 824. Thus, the sensor elements 1318, 1320, 1322 are in fluidconnection with the fluid line and can be used to determine sensor dataof the fluid entering the mixing chamber (not shown in this figure).Thus, in the exemplary embodiment, the sensor elements 1318, 1320, 1322are used to collect data regarding fluid being pumped into the mixingchamber. Referring back to FIG. 12C, sensor elements 1308, 1310, 1312are used to collect data regarding fluid being pumped from the mixingchamber and to the fluid outlet. However, in alternate embodiments, nosensors are or only one set, or only one type of sensor element (i.e.,either temperature conductivity sensor element) is used. Any type ofsensor may be used and additionally, any embodiment of a temperature, aconductivity sensor element or a combined temperature/conductivity,sensor element.

As described above, the exemplary embodiment is one cassette embodimentthat incorporates the exemplary fluid flow-path schematic shown in FIG.8. However, there are alternate embodiments of the cassette thatincorporate many of the same features of the exemplary embodiment, butin a different structural design and with slightly different flow paths.One of these alternate embodiments is the embodiment shown in FIGS.16A-20B.

Referring now to FIGS. 16A-16E, views of an alternate embodiment of thetop plate 1600 are shown. The features of the top plate 1600 arealternate embodiments of corresponding features in the exemplaryembodiment. This alternate embodiment includes two mixing chambers 1622,1624 and three metering pumps. Thus, this embodiment represents theflexibility in the cassette design. In various embodiments, the cassettecan mix any number of fluids, as well, can meter them separately ortogether. FIG. 9 shows a fluid flow-path schematic of the cassette shownin FIGS. 16A-20B.

Referring now to FIGS. 17A-17E, views of an alternate embodiment of themidplate 1700 are shown. FIGS. 18A-18E show views of an alternateembodiment of the bottom plate 1800.

Referring now to FIG. 19A, an assembled alternate embodiment of thecassette 1900 is shown. FIGS. 19C-19D show exploded views of thecassette 1900 where the pod pump membrane 1910, valve membranes 1914 andmetering pump membranes 1912 are shown. The three metering pumps 1616,1618, 1620 can be seen as well as the respective membranes 1912. In thisembodiment, three fluids can be metered and controlled volumes of eachcan be mixed together in the mixing chambers 1622, 1624. FIGS. 20A and20B show a cross sectional view of the assembled cassette 1900.

As this alternate embodiment shows, there are many variations of thepumping cassette and the general fluid schematic shown in FIG. 8. Thus,additional mixing chambers and metering pumps can add additionalcapability to the pumping cassette to mix more than two fluids together.

5.3 Exemplary Embodiments of the Mixing Cassette

In practice, the cassette may be used to pump any type of fluid from anysource to any location. The types of fluid include nutritive,nonnutritive, inorganic chemicals, organic chemicals, bodily fluids orany other type of fluid. Additionally, fluid in some embodimentsincludes a gas, thus, in some embodiments; the cassette is used to pumpa gas.

The cassette serves to pump and direct the fluid and to the desiredlocations. In some embodiments, outside pumps pump the fluid into thecassette and the cassette pumps the fluid out. However, in someembodiments, the pod pumps serve to pull the fluid into the cassette andpump the fluid out of the cassette.

As discussed above, depending on the valve locations, control of thefluid paths is imparted. Thus, the valves being in different locationsor additional valves are alternate embodiments of this cassette.Additionally, the fluid lines and paths shown in the figures describedabove are mere examples of fluid lines and paths. Other embodiments mayhave more, less and/or different fluid paths. In still otherembodiments, valves are not present in the cassette.

The number of pod pumps described above may also vary depending on theembodiment. For example, although the exemplary and alternateembodiments shown and described above include two pod pumps, in otherembodiments, the cassette includes one. In still other embodiments, thecassette includes more than two pod pumps. The pod pumps can be singlepumps or work in tandem to provide a more continuous flow. Either orboth may be used in various embodiments of the cassette.

The various ports are provided to impart particular fluid paths onto thecassette. These ports are not necessarily all used all of the time,instead, the variety of ports provide flexibility of use of the cassettein practice.

The pumping cassette can be used in a myriad of applications. However,in one exemplary embodiment, the pumping cassette is used to mix asolution that includes at least two ingredients/compounds. In theexemplary embodiment, three ingredients are mixed. However, in otherembodiments, less than three or more than three can be mixed by addingmetering pumps mixing chambers, inlets/outlets, valves and fluid lines.These variations to the cassette design are readily discernable.

As used herein, the terms “source ingredient” or “sources ofingredients” refers to ingredients other than the fluid pumped into thecassette from the first fluid inlet. These source ingredients arecontained in a container, or provided by a source, connected to thecassette.

In the exemplary embodiment, the pumping cassette includes the abilityto connect four sources of ingredients to the cassette in addition tothe fluid inlet line. In the exemplary embodiment, the fluid inlet isconnected to a water source. However, in other embodiments, the fluidinlet line is connected to a container of a liquid/fluid solution or toanother source of fluid/liquid.

In the exemplary embodiment, the four additional sources of ingredientscan be four of the same source ingredients, or two of one sourceingredient and two of another. Using two of each source ingredient, orfour of one source ingredient, pumping and mixing can be done in acontinuous manner without having to replace the sources. However,depending on the source, the number of redundant sources of eachingredient will vary. For example, the source could be a connection to avery large container, a smaller container or a seemingly “endless”source. Thus, depending on the volume being pumped and the size of thesource, the number of containers of a source ingredient may vary.

One of the fluid paths described above with respect to FIG. 8 includes apath where the pod pumps pump liquid into the cassette and to two of thesource ingredients sources or containers. This available functionalityof the cassette allows two of the source ingredients to be, at leastinitially, powder that is constituted with the fluid/liquid from thefluid inlet line. As well, there is a valving path for both pod pumpsthat can accomplish pumping fluid to the ingredient sources. Thus, inone embodiment, the valves are controlled for a period of time such thatcontinuous pumping of fluid into the fluid inlet and to two sourceingredient containers is accomplished. This same valving path can beinstituted to the other two source ingredient containers or to one ofthe other two source ingredient containers in addition to or in lieu ofthe valving path shown in FIG. 8. In other embodiments, fluid inletliquid is pumped to only one source ingredient container.

Additionally, in some embodiments, fluid is pumped into the fluid inletand to the source ingredients where the source ingredients are fluid.This embodiment may be used in situations where the fluid inlet fluid isa source ingredient that needs to be mixed with one of the sourceingredients prior to pumping. This functionality can be designed intoany embodiment of the pumping cassette. However, in some embodiments,this valving path is not included.

In the exemplary embodiment, the metering pumps allow for the pumping ofthe source ingredients in known volumes. Thus, careful pumping allowsfor mixing a solution requiring exact concentrations of the variousingredients. A single metering pump could pump multiple sourceingredients. However, as an ingredient is pumped, small amounts of thatingredient may be present in the metering fluid line and thus, couldcontaminate the ingredient and thus, provide for an incorrect assessmentof the volume of that second ingredient being pumped. Therefore, in theexemplary embodiment, at least one metering pump is provided for eachsource ingredient, and thus, a single metering pump is provided for twosources of source ingredients where those two sources contain identicalsource ingredients.

In the exemplary embodiment, for each source ingredient, a metering pumpis provided. Thus, in embodiments where more than two source ingredientsare present, additional metering pumps may be included for eachadditional source ingredient in the pumping cassette. In the exemplaryembodiment, a single metering pump is connected to two sourceingredients because in the exemplary embodiment, these two sourceingredients are the same. However, in alternate embodiments, onemetering pump can pimp more than one source ingredient and be connectedto more than one source ingredient even if they are not the same.

Sensors or sensor elements may be included in the fluid lines todetermine the concentration, temperature or other characteristic of thefluid being pumped. Thus, in embodiments where the source ingredientcontainer included a powder, water having been pumped by the cassette tothe source ingredient container to constitute the powder into solution,a sensor could be used to ensure the correct concentration of the sourceingredient. Further, sensor elements may be included in the fluid outletline downstream from the mixing chamber to determine characteristics ofthe mixed solution prior to the mixed solution exiting the cassettethrough the fluid outlet. Additionally, a downstream valve can beprovided to ensure badly mixed solution is not pumped outside thecassette through the fluid outlet. Discussion of the exemplaryembodiment of the sensor elements is included above.

One example of the pumping cassette in use is as a mixing cassette aspart of a hemodialysis system. The mixing cassette would be used to mixdialysate to feed a dialysate reservoir outside the cassette. Thus, thecassette would be connected to two containers of each citric acid andNaCl/bicarbonate. Two metering pumps are present in the cassette, onededicated to the citric acid and the other to the NaCl/Bicarbonate.Thus, one metering pump works with two source ingredient containers.

In the exemplary embodiment, the NaCl/Bicarbonate is a powder andrequires the addition of water to create the fluid source ingredientsolution. Thus, water is pumped into the first fluid inlet and into thesource containers of NaCl/Bicarbonate. Both pod pumps can pump out ofphase to rapidly and continuously provide the necessary water to thesource containers of NaCl/Bicarbonate.

To mix the dialysate, the citric acid is pumped by a metering pump intoa pod pump and then towards the mixing chamber. Water is pumped into thepod pumps as well, resulting in a desired concentration of citric acid.Sensor elements are located upstream from the mixing chamber todetermine if the citric acid is in the proper concentration and also,the pod pumps can pump additional water towards the mixing chamber ifnecessary to achieve the proper concentration.

The NaCl/Bicarbonate is pumped by the second metering pump and into thefluid outlet line upstream from the mixing chamber. The citric acid andfluid NaCl/Bicarbonate will enter the mixing chamber. The two sourceingredients will then mix and be pumped out the fluid outlets.

In some embodiments, sensor elements are located downstream from themixing chamber. These sensor elements can ensure the concentration ofthe finished solution proper, Also, in some embodiments, a valve may belocated downstream from the fluid outlet. In situations where the sensordata shows the mixing has not been successful or as desired, this valvecan block the dialysate from flowing into the reservoir located outsidethe cassette.

In alternate embodiments of the cassette, addition metering pumps can beincludes to remove fluid from the fluid lines. Also, additional podpumps may be included for additional pumping features. In alternateembodiments of this dialysate mixing process, three metering pumps andtwo mixing chambers are used (as shown in FIG. 9). The citric acid,salt, and bicarbonate are each pumped separately in this embodiment. Onemixing chamber is similar to the one described above, and the secondmixing chamber is used to mix the salt and bicarbonate prior to flowingto the other mixing chamber, where the mixing between the citric acidNaCl/Bicarbonate will be accomplished.

Various embodiments of the cassette for mixing various solutions arereadily discernable. The fluid lines, valving, metering pumps, mixingchambers, pod pumps and inlet/outlets are modular elements that can bemixed and matched to impart the desired mixing functionality onto thecassette.

In various embodiments of the cassette, the valve architecture varies inorder to alter the fluid flow-path. Additionally, the sizes of the podpumps, metering pump and mixing chambers may also vary, as well as thenumber of valves, pod pumps, metering pumps, sensors, mixing chambersand source ingredient containers connected to the cassette. Although inthis embodiment, the valves are volcano valves, in other embodiments,the valves are not volcano valves anti in some embodiments are smoothsurface valves.

6. Exemplary Embodiment of the Middle Cassette

Referring now to FIG. 21, an exemplary embodiment of the fluid schematicof the pumping cassette 3800 is shown. Other schematics are readilydiscernable and one alternate embodiment of the schematic is shown inFIG. 21. Still referring to FIG. 21, the cassette 3800 includes at leastone pod pump 3820, 3828 and at least one vent 3830. The cassette 3800also includes at least one fluid port. In the schematic, a plurality ofports 3804, 3810, 3824, 3826, 3830, 3832, 3846, 3848, 3850, 3852, 3854are shown. However, in alternate embodiments, the number of ports and/orlocations can be different. The plurality of port options presents anumber of possible pumping schematics for any type of fluid for anyfunction.

The cassette additionally includes at least one pod pump 3820, 3828 topump fluid through at least one port and into and/or out of thecassette. The exemplary embodiment includes two pod pumps 3820, 3828.However, in alternate embodiments, one or more pod pumps are included inthe cassette. In the exemplary embodiment, two pod pumps 3820, 3828 mayprovide for continuous or steady flow. The vent 3830 provides a vent toatmosphere for a fluid reservoir fluidly connected to, but outside of,the cassette.

The fluid schematic of the cassette 3800 shown in FIG. 21 may beembodied into various cassette apparatus. Thus, the various embodimentsof the cassette 3800 that include a fluid flow path represented by thefluid schematic shown in FIG. 21 are not the only cassette embodimentsthat may incorporate this or an alternate embodiment of this fluidschematic. Additionally, the types of valves, the order of actuation ofthe valves, and the number of pumps may vary in various cassetteembodiments of this fluid schematic. Also, additional features may bepresent in embodiments of the pumping cassette that are not representedin the schematic or on the cassette embodiments shown and describedherein.

Still referring to FIG. 21, in one scenario, fluid enters the cassettethrough a port 3810 and is pumped to either a first pump fluid path 3812or a second pump fluid path 3818. In one embodiment, pump inlet valves3808, 3814 alternately open and close, and the valve 3808, 3814 that isopen at any given time allows the fluid to flow into its respectivefluid path 3812, 3818 and into the respective pod pump 3820, 3828. Therespective pump inlet valve 3808, 3814 then closes, and thecorresponding pump outlet valve 3816, 3822 opens. The fluid is pumpedout of the pod pump 3820, 3828 and through first fluid outlet 3824.However, in other embodiments, both valves 3808, 3814 open and close atthe same time. In some embodiments, no valves are in the cassette.

A vent 3830 provides a location for a reservoir or other container orfluid source to vent to atmosphere. In some embodiments, the source ofthe first fluid is connected to the vent 3830. A valve 3802 controls theventing pathway.

Although in one scenario, fluid is pumped into port 3810, in otherembodiments fluid is pumped into the cassette through any of the ports3804, 3824, 3826, 3830, 3832, 3846, 3848, 3850, 3852, 3854 and then outof the cassette through any of the ports 3804, 3810, 3824, 3826, 3830,3832, 3846, 3848, 3850, 3852, 3854. Additionally, the pod pumps 3820,3828 in various embodiments pump fluid in the opposite direction thandescribed above.

In general, the cassette 3800 provides pumping power to pump fluid aswell as fluid flow paths between ports and around the cassette.

In one embodiment, the one or more ports 3804, 3810, 3824, 3826, 3830,3832, 3846, 3848, 3850, 3852, 3854 are attached to a filter or othertreatment area for the fluid being pumped out of the cassette. In someembodiments, pod pumps 3820, 3828 provide enough pumping force to pushthe fluid through a filter or other treatment area.

In some embodiments, the pumping cassette includes additional fluidpaths and one or more additional pod pumps. Additionally, the cassettein some embodiments includes additional venting paths.

The various flow paths possible in the cassette, represented by oneembodiment in FIG. 21, are controlled by the valves 3802, 3808, 3814,3816, 3822, 3836, 38338, 3840, 3842, 3844, 3856. Opening and closing thevalves 3802, 3808, 3814, 3816, 3822, 3836, 3838, 3840, 3842, 3844, 3856in different orders leads to very different fluid pumping paths andoptions for pumping. Referring now to FIGS. 23C, 24A, 24B and 24C, thevarious valves and ports are shown on a n exemplary embodiment of thecassette.

In some embodiments of the pumping cassette, more valves are included oradditional flow paths and/or ports are included. In other embodiments,there are a smaller number of valves, flow path and/or ports. In someembodiments of the cassette, the cassette may include one or more airtraps, one or more filters, and/or one or more check valves.

The embodiments of the fluid flow-path schematic shown in FIG. 21, oralternate embodiments thereof, can be embodied into a structure. In theexemplary embodiment, the structure is a three plate cassette withactuating membranes. Alternate embodiments of the cassette are alsodescribed below.

Referring now to FIGS. 23A and 23B, the outer side of the top plate 3900of the exemplary embodiment of the cassette is shown. The top plate 3900includes one half of the pod pumps 3820, 3828. This half is thefluid/liquid half where the source fluid will flow through. The inletand outlet pod pump fluid paths are shown. These fluid paths lead totheir respective pod pumps 3820, 3828.

The pod pumps 3820, 3828 include a raised flow path 3908, 3910. Theraised flow path 3908, 3910 allows for the fluid to continue to flowthrough the pod pumps 3820, 3828 after the membrane (not shown) reachesthe end of stroke. Thus, the raised flow path 3908, 3910 minimizes themembrane causing air or fluid to be trapped in the pod pump 3820, 3828or the membrane blocking the inlet or outlet of the pod pump 3820, 3828,which would inhibit flow. The raised flow path 3908, 3910 is shown inthe exemplary embodiment having particular dimensions. In alternateembodiments, the raised flow path 3908, 3910 is larger or narrower, orin still other embodiments, the raised flow path 3908, 3910 can be anydimension as the purpose is to control fluid flow so as to achieve adesired flow rate or behavior of the fluid. Thus, the dimensions shownand described here with respect to the raised flow path, the pod pumps,the valves, or any other aspect are mere exemplary and alternateembodiments. Other embodiments are readily apparent.

FIGS. 23C and 23D show the inner side of the top plate 3900 of theexemplary embodiment of the cassette. FIG. 23E shows a side view of thetop plate 3900.

Referring now to FIGS. 24A and 24B, the fluid/liquid side of themidplate 31000 is shown. The areas complementary to the fluid paths onthe inner top plate shown in FIGS. 23C and 23D are shown. These areasare slightly raised tracks that present a surface finish that isconducive to laser welding, which is one mode of manufacturing in theexemplary embodiment. Other modes of manufacturing the cassette arediscussed above. Referring to FIGS. 24A and 24B, the ports of theexemplary embodiment of the cassette are labeled corresponding to theschematic shown and described above with respect to FIG. 21. One port isnot labeled, port 3852. This port is best seen in FIG. 23C.

Referring next to FIGS. 24C and 24D, the air side, or side facing thebottom plate (not shown, shown in FIGS. 25A-25E) of the midplate 31000is shown according to the exemplary embodiment. The air side of thevalve holes 3802, 3808, 3814, 3816, 3822, 3836, 3838, 3840, 3842, 3844,3856 correspond to the holes in the fluid side of the midplate 31000(shown in FIGS. 24A and 24B). As seen in FIGS. 26C and 26D, membranes31220 complete pod pumps 3820, 3828 while membranes 31222 completevalves 3802, 3808, 3814, 3816, 3822, 3836, 38338, 3840, 3842, 3844,3856. The valves 3802 3808, 3814, 3816, 3822, 3836, 3838, 3840, 3842,3844, 3856 are actuated pneumatically, and as the membrane is pulledaway from the holes, liquid/fluid is allowed to flow. As the membrane ispushed toward the holes, fluid flow is inhibited. The fluid flow isdirected by the opening and closing of the valves 3802, 3808, 3814,3816, 3822, 3836, 3838, 3840, 3842, 3844, 3856. The exemplary embodimentof the valve is a volcano valve, shown in described above with respectto FIGS. 2A and 2B. One embodiment of the valve membrane 31222 is shownin FIG. 2E, alternate embodiments are shown in FIGS. 2F-2G.

Referring next to FIGS. 25A and 25B, the inner view of the bottom plate31100 is shown. The inside view of the pod pumps 3820, 3828, and thevalves 3802, 3808, 3814, 3816, 3822, 3836, 3838, 3840, 3842, 3844, 3856actuation/air chamber is shown. The pod pumps 3820, 3828, and the valves3802, 3808, 3814, 3816, 3822, 3836, 3838, 3840, 3842, 3844, 3856 areactuated by a pneumatic air source. Referring now to FIGS. 25C and 25D,the outer side of the bottom plate 31100 is shown. The source of air isattached to this side of the cassette. In one embodiment, tubes connectto the tubes on the valves and pumps 1102. In some embodiments, thevalves are ganged, and more than one valve is actuated by the same airline.

Referring now to FIGS. 26A and 26B, an assembled cassette 31200 isshown. An exploded view of the assembled cassette 31200 shown in FIGS.26A and 26B is shown in FIGS. 26C and 26D. In these views, the exemplaryembodiment of the pod pump membranes 31220 is shown. The exemplaryembodiment includes membranes shown in FIGS. 5A-5D. The gasket of themembrane provides a seal between the liquid chamber (in the top plate3900) and the air/actuation chamber (in the bottom plate 31100). In someembodiments, including those shown in FIGS. 5B-5D, texture on the domeof the membranes 31220 provide, amongst other features, additional spacefor air and liquid to escape the chamber at the end of stroke. Inalternate embodiments of the cassette, the membranes shown in FIGS.6A-6G may be used. Referring to FIGS. 6A-6G, as discussed in greaterdetail above, these membranes include a double gasket 62, 64. The doublegasket 62, 64 feature would be preferred in embodiments where both sidesof the pod pump include liquid or in applications where sealing bothchambers sides is desired. In these embodiments, a rim complementary tothe gasket or other feature (not shown) would be added to the innerbottom plate 31100 for the gasket 62 to seal the pod pump chamber in thebottom plate 31100.

Referring now to FIG. 27, a cross sectional view of the pod pumps 3828in the cassette is shown. The details of the attachment of the membrane31220 can be seen in this view. Again, in the exemplary embodiment, themembrane 31220 gasket is pinched by the midplate 31000 and the bottomplate 31100. A rim on the midplate 31000 provides a feature for thegasket to seal the pod pump 3828 chamber located in the top plate 3900.

Referring next to FIG. 27, this cross sectional view shows the valves3834, 3836 in the assembled cassette. The membranes 31220 are shownassembled and are held in place, in the exemplary embodiment, by beingsandwiched between the midplate 31000 and the bottom plate 31100.

Still referring to FIG. 27, this cross sectional view also shows a valve3822 in the assembled cassette. The membrane 31222 is shown held inplace by being sandwiched between the midplate 31000 and the bottomplate 31100.

As described above, the exemplary embodiment described above representsone cassette embodiment that incorporates the exemplary fluid flow-pathschematic shown in FIG. 21. However, there are alternate embodiments ofthe cassette that incorporate many of the same features of the exemplaryembodiment, but in a different structural design. One of these alternateembodiments is the embodiment shown in FIGS. 28A-34B. An alternateschematic is shown in FIG. 22. This schematic, although similar to theschematic shown in FIG. 21, can be viewed to show the fluid paths of thealternate embodiment shown FIGS. 28A-34B.

Referring now to FIGS. 28A-28E, views of an alternate embodiment of thetop plate 31400 are shown. The features of the top plate 31400 arealternate embodiments of corresponding features in the exemplaryembodiment. Referring to FIGS. 28C and 28D, the pod pumps 3820, 3828 arecut into the inside of the top plate 1400. And, as can be seen in FIGS.28A and 28B, the pod pumps 3820, 3828 do not protrude on the outside topplate 31400.

In this embodiment, when the cassette is assembled, as shown in FIGS.33A-33B, the plates 31400, 31600, 31800 are sealed from each other usinggaskets shown in FIGS. 29 and 31 as 31500 and 31700 respectively.Referring now to the exploded view of the cassette in FIGS. 33C and 33D,the pod pump membranes 31220 and valving membranes 31222 are shown.Additionally, in some embodiments, a check valve housing cell 31114 isadditionally included.

Still referring to FIGS. 33C-33D, in this alternate embodiment, thecassette 1900 is assembled with connection hardware 31910. Thus, thecassette 31900 is mechanically assembled and held together by connectionhardware 31910. In this embodiment, the connection hardware is screwsbut in other embodiments, the connection hardware 31910 is metal posts.Any connection hardware may be used in alternate embodiments including,but not limited, to rivets, shoulder bolts, and bolts. In additionalalternate embodiments, the plates are held together by an adhesive.

Still referring to FIGS. 33C and 33D, check valves 31920 are shown. Inthis embodiment, the check valves 31920 are duck-bill check valves, butin other embodiments, the check valves can be any type of check valve.In this embodiment, the check valves are held by a check valve cell31922. Additionally, in some embodiments, more check valves are used inthe cassette. For example, in this embodiment, and in some embodimentsof the exemplary embodiment described above that includes check valves,additional check valve holders 31926, 31928 are shown. These provideholders for additional check valves. In still other embodiments, an airtrap 31924 may be included as shown in this embodiment. Referring now toFIGS. 35A-35D, one embodiment of the duck-bill check valve is shown.However, in other embodiments, any check valve or alternate embodimentsof a duck-bill check valve may be used.

Referring now to FIGS. 34A and 34B, cross sectional views of theassembled cassette and the gaskets' 31500, 31700 relation to theassembled cassette assembly is shown.

In the alternate embodiment, the gaskets 31500, 31700 are made fromsilicone, but in other embodiments, the gaskets 31500, 31700 may be madefrom other materials. Still referring to FIGS. 34A and 34B, theconnection hardware 31910 is shown. Referring to FIG. 34B, the crosssectional view shows the duck-bill check valves 31920 in the assembledcassette.

6.1 Exemplary Embodiments of the Middle Cassette

In practice, the cassette may be used to pump any type of fluid from anysource to any location. The types of fluid include nutritive,nonnutritive, inorganic chemicals, organic chemicals, bodily fluids, orany other type of fluid. Additionally, fluid in some embodiments includea gas, thus, in some embodiments, the cassette is used to pump a gas.

The cassette serves to pump and direct tie fluid from and to the desiredlocations. In some embodiments, outside pumps pump the fluid into thecassette and the cassette pumps the fluid out. However, in someembodiments, the pod pumps serve to pull the fluid into the cassette andpump the fluid out of the cassette.

As discussed above, depending on the valve locations, control of thefluid paths is imparted. Thus, the valves being in different locationsor additional valves are alternate embodiments of this cassette.Additionally, the fluid lines and paths shown in the figures describedabove are mere examples of fluid lines and paths. Other embodiments mayhave more, less, and/or different fluid paths. In still otherembodiment, valves are not present in the cassette.

The number of pod pumps described above may also vary depending on theembodiment. For example, although the exemplary and alternateembodiments shown and described above include two pod pumps, in otherembodiments, the cassette includes one. In still other embodiments, thecassette includes more than two pod pumps. The pop pumps can be singlepumps or work in tandem to provide a more continuous flow. Either orboth may be used in various embodiments of the cassette.

The terms inlet and outlet as well as fluid paths are used fordescription purposes only. In other embodiments, an inlet can be anoutlet. The denotations simply refer to separate entrance areas into thecassette.

The designations given for the fluid inlets (which can also be fluidoutlets) for example, first fluid outlet, second fluid outlet, merelyindicate that a fluid may travel out of or into the cassette via thatinlet/outlet. In some cases, more than one inlet/outlet on the schematicis designated with an identical name. This merely describes that all ofthe inlet/outlets having that designation are pumped by the samemetering pump or set of pod pumps (which in alternate embodiments, canbe a single pod pump).

The various ports are provided to impart particular fluid paths onto thecassette. These ports are not necessarily all used all of the time,instead, the variety of ports provide flexibility of use of the cassettein practice.

Referring again to FIG. 21, one embodiment provides for a fluidreservoir to be fluidly attached to the vent port 3830 allowing for thereservoir to vent to atmosphere. Additionally, in some embodiments, anFMS reference chamber is fluidly attached to the reservoir and thus, asfluid is added or removed from the reservoir, the volume may bedetermined using the FMS. Some embodiments include additional vent portsin the cassette and thus, some embodiments of the cassette may beattached to more than one fluid reservoir.

One embodiment includes a fluid line extending from port 3850 to port3848 and controlled by valves 3838, 3836. In one embodiment, port 3848may be fluidly attached to a reservoir. As such, port 3810 may also beattached to the same reservoir. Thus, in one embodiment, port 3850provides a fluid line to the reservoir, and port 3810 provides a fluidline suck that the pod pumps pump fluid from the reservoir into thecassette. In some embodiments, valve 3858 controls a bypass line fromthe reservoir to another fluid line controlled by valve 3842.

Some embodiments may include an air trap within the fluid lines and/orat least one sensor. The sensor can be any sensor having a capability todetermine any fluid or non-fluid sensor data. In one embodiment, threesensor elements are included in a single fluid line. In someembodiments, more than one fluid line includes the three sensorelements. In the three sensor element embodiment, two of the sensorelements are conductivity sensor elements and the third sensor elementis a temperature sensor element. The conductivity sensor elements andtemperature sensor element can be any conductivity or temperature sensorin the art. In one embodiment, the conductivity sensors are graphiteposts. In other embodiments, the conductivity sensor elements are postsmade from stainless steel, titanium, platinum, or any other metal coatedto be corrosion resistant and still be electrically conductive. Theconductivity sensor elements will include an electrical lead thattransmits the probe information to a controller or other device. In oneembodiment, the temperature sensor is a thermister potted in a stainlesssteel probe. However, in alternate embodiments, a combinationtemperature and conductivity sensor elements is used similar to the onedescribed in co-pending U.S. patent application entitled SensorApparatus Systems, Devices and Methods filed Oct. 12, 2007 (U.S.application Ser. No. 11/871,821).

In alternate embodiments, there are either no sensors in the cassette oronly a temperature sensor, only one or more conductivity sensors or oneor more of another type of sensor.

7. Exemplary Embodiment of the Balancing Cassette

Referring now to FIG. 36, an exemplary embodiment of the fluid schematicof the balancing pumping and metering cassette 4800 is shown. Otherschematics are readily discernable. The cassette 4800 includes at leastone pod pump 4828, 4820 and at least one balancing pod 4822, 4812. Thecassette 4800 also includes a first fluid inlet 4810, where a firstfluid enters the cassette. The first fluid includes a flow rate providedoutside the cassette 4800. The cassette 4800 also includes a first fluidoutlet 4824 where the first fluid exits the cassette 4800 having a flowrate provided by one of the at least one pod pumps 4828. The cassette4800 includes a second fluid inlet 4826 where the second fluid entersthe cassette 4800, and a second fluid outlet 4816 where the second fluidexits the cassette.

Balancing pods 4822, 4812 in the cassette 4800 provide for a desiredbalance of volume of fluid pumped into and out of the cassette 4800,i.e., between the first fluid and the second fluid. The balancing pods4822, 4812, however, may be bypassed by way of the metering pump 4830.The metering pump 4830 pumps a volume of second fluid (or first fluid inother embodiments) out of the fluid line, bypassing the balancing pod4822, 4812. Thus, a smaller or reduced volume (i.e., a “new” volume) ofthe fluid that has been removed by the metering pump 4830 will actuallyenter the balancing pod 4822, 4812 and thus, the metering pump 4830functions to provide a “new” volume of second fluid by removing thedesired volume from the fluid path before the second fluid reaches thebalancing pod 4822, 4812 (or in other embodiments, removing first fluidthe desired volume from the fluid path before the second fluid reachesthe balancing pod 4822, 4812) resulting in less first fluid (or in otherembodiments second fluid) being pumped for that pump cycle.

The fluid schematic of the cassette 4800 show in FIG. 36 may be embodiedinto various cassette apparatus. Thus, the embodiments of the cassette4800 including the fluid schematic shown in FIG. 36 are not the onlycassette embodiments that may incorporate this or an alternateembodiment of this fluid schematic. Additionally, the types of valves,the ganging of the valves, the number of pumps and chambers may vary invarious cassette embodiments of this fluid schematic.

Referring still to FIG. 36, a fluid flow-path schematic 4800 is shown.The fluid flow-path schematic 4800 is described herein corresponding tothe flow paths in one embodiment of the cassette. The exemplaryembodiment of the midplate 4900 of the cassette is shown in FIG. 49Awith the valves corresponding to the fluid flow-path schematic in FIG.36 indicated. The valving side of the midplate 4900 shown in FIG. 38Acorresponds to the fluid side shown in FIG. 38B.

Referring first to FIG. 36 with FIG. 38A, a first fluid enters thecassette at the first fluid inlet 4810. The first fluid flows tobalancing pod A 4812. Balancing pod A 412 is a balancing pod asdescribed above. Balancing pod A 4812 initially contained a first volumeof second fluid. When the first fluid flows into the balancing pod A4812, the membrane forces the second fluid out of balancing pod A 4812.The second fluid flows through the drain path 4814 and out the firstfluid outlet 4816.

At the same time, pod pump 4820 includes a volume of second fluid. Thevolume of second fluid is pumped to balancing pod B 4822. Balancing podB 4822 contains a volume of first fluid, and this volume of first fluidis displaced by the volume of second fluid. The volume of first fluidfrom balancing pod B 4822 flows to the second fluid outlet 4824 andexits the cassette. A volume of a second fluid enters the cassette atfluid inlet two 4826 and flows to pod pump A 4828.

Referring still to FIG. 36 with FIG. 38A, the second fluid is pumpedfrom pod pump A 4828 to balancing pod A 4812. The second fluid displacesthe first fluid in balancing pod A 4812. The first fluid from balancingpod A 4812 flows to the second fluid outlet 4824.

First fluid flows into the cassette through the first fluid inlet 4810and flows to balancing pod B 4822. The first fluid displaces the secondfluid in balancing pod B 4822, forcing the second fluid to flow out ofthe cassette through the first fluid outlet 4816. Second fluid flowsinto the cassette through the second fluid inlet 4826 and to pod pump B4820.

The metering pump can be actuated at a time and its function is toremove fluid from the fluid path in order to bypass the balancing pod.Thus, any volume of fluid removed would act to decrease the volume ofthe other fluid flowing out of the second fluid outlet 4824. Themetering pump is independent of the balancing pods 4812, 4822 and thepod pumps 4820, 4828. The fluid enters through fluid inlet two 4826 andis pulled by the metering pump 4830. The metering pump then pumps thevolume of fluid through the second fluid outlet 4816.

Although in the embodiment of the fluid schematic shown in FIG. 36, themetering pump is described only with respect to second fluid enteringthe cassette through fluid inlet two 4826, the metering pump can easilybypass first fluid entering the cassette through fluid inlet one 4810.Thus, depending on whether the desired end result is to have less of thefirst fluid or less of the second fluid, the metering pump and valvesthat control the fluid lines in the cassette can perform accordingly toaccomplish the result.

In the exemplary fluid flow-path embodiment shown in FIG. 36, andcorresponding structure of the cassette shown in FIG. 38A, valves areganged such that they are actuated at the same time. In the preferredembodiment, there are four gangs of valves 4832, 4834, 4836, 4838. Inthe preferred embodiment, the ganged valves are actuated by the same airline. However, in other embodiments, each valve has its own air line.Ganging the valves as shown in the exemplary embodiment creates thefluid-flow described above. In some embodiments, ganging the valves alsoensures the appropriate valves are opened and closed to dictate thefluid pathways as desired.

In the exemplary embodiment, the fluid valves are volcano valves, asdescribed in more detail in this specification. Although the fluidflow-path schematic has been described with respect to a particular flowpath, in various embodiments, the flow paths can change based on theactuation of the valves and the pumps. Additionally, the terms inlet andoutlet as well as first fluid and second fluid are used for descriptionpurposes only. In other embodiments, an inlet can be an outlet, as wellas, a first and second fluid may be different fluids or the same fluidtypes or composition.

Referring now to FIGS. 39A-39E, the top plate 41000 of the exemplaryembodiment of the cassette is shown. Referring first to FIGS. 39A and39B, the top view of the top plate 41000 is shown. In the exemplaryembodiment, the pod pumps 4820, 4828 and the balancing pods 4812, 4822on the top plate, are formed in a similar fashion. In the exemplaryembodiment, the pod pumps 4820, 4828 and balancing pods 4812, 4822, whenassembled with the bottom plate, have a total volume of capacity of 38ml. However, in various embodiments, the total volume capacity can begreater or less than in the exemplary embodiment. The first fluid inlet4810 and the second fluid outlet 4816 are shown.

Referring now to FIGS. 39C and 39D, the bottom view of the top plate41000 is shown. The fluid paths are shown in this view. These fluidpaths correspond to the fluid paths shown in FIG. 38B in the midplate4900. The top plate 41000 and take top of the midplate form the liquidor fluid side of the cassette for the pod pumps 4820, 4828 and for oneside o the balancing pods 4812, 4822. Thus, most of the liquid flowpaths are on the top and midplates. The other side of the balancingpods' 4812, 4822 flow paths is located on the inner side of the bottomplate, not shown here, shown in FIGS. 40A and 41B.

Still referring to FIGS. 39C and 39D, the pod pulps 4820, 4828 andbalancing pods 4812, 4822 include a groove 41002. The groove 41002 isshown having a particular shape, however, in other embodiments, theshape of the groove 41002 can be any shape desirable. The shape shown inFIGS. 39C and 39D is the exemplary embodiment. In all embodiments of thegroove 41002, the groove forms a path between the fluid inlet side andthe fluid outlet side of the pod pumps 4820, 4828 and balancing pods4812, 4822.

The groove 41002 provides a fluid path whereby when the membrane is atthe end of stroke, there is still a fluid path between the inlet andoutlet such that the pockets of fluid or air do not get trapped in thepod pump or balancing pod. The groove 41002 is included in both theliquid and air sides of the pod pumps 4820, 4828 and balancing pods4812, 4822 (see FIGS. 40A and 41B with respect to the air side of thepod pumps 4820, 4828 and the opposite side of the balancing pods 4812,4822).

The liquid side of the pod pumps 4820, 4828 and balancing pods 4812,4822, in the exemplary embodiment, include a feature whereby the inletand outlet flow paths are continuous while the outer ring 41004 is alsocontinuous. This feature allows for the seal, formed with the membrane(not shown) to be maintained.

Referring to FIG. 39E, the side view of the exemplary embodiment of thetop plate 41000 is shown. The continuous outer ring 41004 of the podpumps 4820, 4828 and balancing pods 4812, 4822 can be seen.

Referring now to FIGS. 40A-41E, the bottom plate 41100 is shown.Referring first to FIGS. 40A and 41B, the inside surface of the bottomplate 41100 is shown. The inside surface is the side that contacts thebottom surface of the midplate (not shown, see FIG. 41B). The bottomplate 41100 attaches to the air lines (not shown). The correspondingentrance holes for the air that actuates the pod pumps 4820, 4828 andvalves (not shown, see FIG. 41B) in the midplate can be seen 41106.Holes 41108, 41110 correspond to the second fluid inlet and second fluidoutlet shown in FIGS. 41C, 4824, 4826 respectively. The correspondinghalves of the pod pumps 4820, 4828 and balancing pods 4812, 4822 arealso shown, as are the grooves 41112 for the fluid paths. Unlike the topplate, the bottom plate corresponding halves of the pod pumps 4820, 4828and balancing pods 4812, 4822 make apparent the difference between thepod pumps 4820, 4828 and balancing pods 4812, 4822. The pod pumps 4820,4828 include only a air path on the second half in the bottom plate,while the balancing pod 4812, 4822 have identical construction to thehalf in the top plate. Again, the balancing pods 4812, 4822 balanceliquid, thus, both sides of the membrane, not shown, will include aliquid fluid path, while the pod pumps 4820, 4828 are pressure pumpsthat pump liquid, thus, one side includes a liquid fluid path and theother side, shown in the bottom plate 41100, includes an air actuationchamber or air fluid path.

In the exemplary embodiment of the cassette, sensor elements areincorporated into the cassette so as to discern various properties ofthe fluid being pumped. In one embodiment, the three sensor elements areincluded. In the exemplary embodiment, the sensor elements are locatedin the sensor cell 41114. The cell 41114 accommodates three sensorelements in the sensor element housings 41116, 41118, 41120. In theexemplary embodiment, two of the sensor housings 41116, 41118accommodate a conductivity sensor element and the third sensor elementhousing 41120 accommodates a temperature sensor element. Theconductivity sensor elements and temperature sensor elements can be anyconductivity or temperature sensor elements in the art. In oneembodiment, the conductivity sensor elements are graphite posts. Inother embodiments, the conductivity sensor elements are posts made fromstainless steel, titanium, platinum or any other metal coated to becorrosion resistant and still be electrically conductive. Theconductivity sensor element will include an electrical lead thattransmits the probe information to a controller or other device. In oneembodiment, the temperature sensor is a thermister potted in a stainlesssteel probe. However, in alternate embodiments, a combinationtemperature and conductivity sensor elements is used similar to the onedescribed in co-pending U.S. patent application entitled SensorApparatus Systems, Devices and Methods filed Oct. 12, 2007 (U.S.application Ser. No. 11/871,821).

In this embodiment, the sensor cell 41114 is a single opening to thefluid line connection to the fluid line.

In alternate embodiments, there are either no sensors in the cassette oronly a temperature sensor, only one or more conductivity sensors or oneor more of another type of sensor.

Still referring to FIGS. 40A and 41B, the actuation side oft themetering pup 4830 is also shown as well as the corresponding airentrance hole 41106 for the air that actuates the pump.

Referring now to FIGS. 41C and 41D, the outer side of the bottom plate41100 is shown. The valve, pod pumps 4820, 4828 and metering pump 4830air line connection points 41122 are shown. Again, the balancing pods4812, 4822 do not have air line connect points as the are not actuatedby air. As well, the corresponding openings in the bottom plate 41100for the second fluid outlet 4824 and second fluid inlet 4826 are shown.

Referring now to FIG. 41E, a side view of the bottom plate 41100 isshown. In the side view, the rim 41124 that surrounds the inner bottomplate 41100 can be seen. The rim 41124 is raised and continuous,providing for a connect point for the membrane (not shown). The membranerests on this continuous and raised rim 41124 providing for a sealbetween the half of the pod pumps, 4820, 4828 and balancing pods 4812,4822 in the bottom plate 41100 and the half of the pod pumps 4820, 4828and balancing pods 4812, 4822 in the top plate (not shown, see FIGS.39A-39D).

7.1 Membranes

In the exemplary embodiment, the membrane is a double o-ring membrane asshown in FIG. 6A. However, in some embodiments, a double o-ring membranehaving texture, including, but not limited to, the various embodimentsin FIGS. 6B-6F may be used.

Referring now to FIGS. 42A and 42B, the assembled exemplary embodimentof the cassette 41200 is shown. FIGS. 42C and 42D are exploded views ofthe exemplary embodiment of the cassette 41200. The membranes 41210 areshown. As can be seen from FIGS. 42C and 42D, there is one membrane41220 for each of the pods pumps and balancing pods. In the exemplaryembodiment, the membrane for the pod pumps and the balancing pods areidentical. The membrane in the exemplary embodiment is a double o-ringmembrane as shown in FIGS. 6A-6B. However, in alternate embodiments, anydouble o-ring membrane may be used, including, but not limited to, thevarious embodiments shown in FIGS. 6C-6F. However, in other embodiments,the double o-ring membrane is used in the balancing pods, but a singleo-ring membrane, as shown in FIGS. 4A-4D is used in the pod pumps.

The membrane used in the metering pump 41224, in the preferredembodiment, is shown in more detail in FIG. 5G, with alternateembodiments shown in FIGS. 5E, 5F and 5H. The membrane used in thevalves 41222 is shown in more detail in FIG. 2E, with alternateembodiments shown in FIGS. 2F-2G. However, in alternate embodiments, themetering pump membrane as well as the valve membranes may containtextures, for example, but not limited to, the textures shown on the podpump/balancing pod membranes shown in FIGS. 5A-5D.

One embodiment of the conductivity sensor elements 41214, 41216 and thetemperature sensor 41218, which make up the sensor cell 41212, are alsoshown in FIGS. 42C and 42D. Still referring to FIGS. 42C and 42D, thesensor cell housing 41414 includes areas on the bottom plate 41100 andthe midplate 4900. O-rings seal the sensor housing 41414 from the fluidlines located on the upper side of the midplate 4900 shown in FIG. 42Cand the inner side of the top plate 41000 shown in FIG. 42D. However, inother embodiments, an o-ring is molded into the sensor cell, or anyother method of sealing can be used.

7.2 Cross Sectional Views

Referring now to FIGS. 43A-43C, various cross sectional views of theassembled cassette are shown. Referring first to FIG. 43A, the membrane41220 is shown in a balancing pod 4812 and a pod pump 4828. As can beseen from the cross section, the double o-ring of the membrane 41220 issandwiched by the midplate 4900, the bottom plate 41100 and the topplate 41000.

Referring now to FIG. 43B, the two conductivity sensor elements 41214,41216 and the temperature sensor element 41218 are shown. As can be seenfrom the cross section, the sensor elements 41214, 41216, 41218 are inthe fluid line 41302. Thus, the sensor elements 41214, 41216, 41218 arein fluid connection with the fluid line and can determine sensor data ofthe first fluid entering the first fluid inlet 4810. Referring now toFIG. 43C, this cross sectional view shows the metering pump 4830 as wellas the structure of the valves.

As described above, the exemplary embodiment is one cassette embodimentthat incorporates the exemplary fluid flow-path schematic shown in FIG.36. However, there are alternate embodiments of the cassette thatincorporate many of the same features of the exemplary embodiment, butin a different structural design. Additionally, there are alternateembodiment fluid flow paths, for example, the fluid flow path schematicshown in FIG. 37. The alternate embodiment cassette structurecorresponding to this schematic is shown in FIGS. 44A-48.

Referring now to FIGS. 44A-44E, views of an alternate embodiment of thetop plate 41400 are shown. The features of the top plate 41400 arealternate embodiments of corresponding features in the exemplaryembodiment.

Referring now to FIGS. 45A-45E, views of an alternate embodiment of themidplate 41500 are shown. FIGS. 46A-46E show views of an alternateembodiment of the bottom plate 41600.

Referring now to FIGS. 47A-47B, an assembled alternate embodiment of thecassette 41700 is shown. FIGS. 47C-47D show exploded views of thecassette 41700. FIG. 47E is a cross sectional view of the assembledcassette 41700.

Referring now to FIGS. 48A-52B another alternate embodiment of thecassette is shown. In this embodiment, when the cassette is assembled,as shown in FIGS. 51A-51B, the plates 41800, 41900, 42000 are sealedfrom each other using gaskets. Referring to FIGS. 51C-51D, the gaskets42110, 42112 are shown. This embodiment additionally includes membranes(not shown). FIG. 52A is a cross sectional view of the assembledcassette, the gaskets 42110, 42112 relation to the assembled cassetteassembly is shown.

7.3 Exemplary Embodiments of the Balancing Cassette

The pumping cassette can be used in a myriad of applications. However,in one exemplary embodiment, the pumping cassette is used to balancefluid going into the first fluid inlet and out the first fluid outletwith fluid coming into the cassette through the second fluid inlet andexiting the cassette through the second fluid outlet (or vice versa).The pumping cassette additionally provides a metering pump to remove avolume of fluid prior to that volume affecting the balancing chambers oradds a volume of fluid prior to the fluid affecting the balancingchambers.

The pumping cassette may be used in applications where it is criticalthat two fluid volumes are balanced. Also, the pumping cassette impartsthe extra functionality of metering or bypassing a fluid out of thefluid path, or adding a volume of the same fluid or a different fluidinto the fluid path. The flow paths shown in the schematic arebi-directional, and various flow paths may be created by changing thevalve locations and or controls, or adding or removing valves.Additionally, more metering pumps, pod pumps and/or balancing pods maybe added, as well as, more or less fluid paths and valves. Additionally,inlets and outlets may be added as well, or the number of inlets oroutlets may be reduced.

One example is using the pumping cassette as an inner dialysate cassetteas part of a hemodialysis system. Clean dialysate would enter thecassette through the first fluid inlet and pass through the sensorelements, checking if the dialysate is at the correct concentrationand/or temperature. This dialysate would pass through the balancingchambers and be pumped through the first fluid outlet and into adialyzer. The second fluid in this case is used or impure dialysate fromthe dialyzer. This second fluid would enter through the second fluidinlet and balance with the clean dialysate, such that the amount ofdialysate that goes into the dialyzer is equal to the amount that comesout.

The metering pump may be used to remove additional used dialysate priorto that volume being accounted for in a balancing chamber, thus,creating a “false” balancing chamber through an ultra filtration (“UF”)bypass. The situation is created where less clean dialysate by a volumeequaled to the bypassed volume will enter the dialyzer.

In this embodiment, the valves controlling fluid connections to thebalancing pods shall be oriented such that the volcano feature of thevalve is on the fluid port connected to the balancing pod. Thisorientation directs most of the fluid displaced by the valve as it isthrown away from the balancing pod.

The valves controlling fluid connections to the UF pump shall beoriented such that the volcano feature of the valve is on the fluid portconnected to the pumping chamber. In the exemplary embodiment, thenominal stroke volume of each inside dialysate pump chamber shall be 38ml. The nominal volume of each balancing pod shall be 38 ml. The strokevolume of the UF pump shall be 1.2 ml+/−0.05 ml. The inner dialysatepump low-pressure pneumatic variable values shall vent to ambientatmospheric pressure. This architecture feature minimizes the chancethat dissolved gas will leave the dialysate while inside of thebalancing chambers. Other volumes of pod pumps, balancing pods andmetering pumps are easily discernable and would vary depending on theapplication. Additionally, although the embodiment described discussesventing to ambient, in other applications, negative pressure can beadministered.

In various embodiments of the cassette, the valve architecture varies inorder to alter the fluid flow path. Additionally, the sizes of the podpumps, metering pump and balancing pods may also vary, as well as thenumber of valves, pod pumps, metering pumps and balancing pods. Althoughin this embodiment, the valves are volcano valves, in other embodiments,the valves are not volcano valves and in some embodiments are smoothsurface valves.

8. Exemplary Embodiment of the Cassette System Integrated

As described above, a mixing cassette may be used to mix dialysate, andthen send the dialysate to a storing vessel or reservoir. The middlecassette provides a vent for a container and a variety of fluid linesand ports, and the balancing cassette provides a system for balancingthe volume of fluid that enters a cassette in one direction with thevolume that enters the cassette in another direction. Additionally, thebalancing cassette provides a metering function, where a volume of fluidfrom one direction may be pumped such that it bypasses the balancingchambers and does not affect the balancing volumes. In some embodiments,these three cassettes may be combined into a system. Fluid lines canconnect the cassettes such that a cassette system integrated is formed.However, various hoses can be difficult to manage and also, get tangled,removed from the ports or the connection may be disrupted in one of avariety of ways.

One embodiment of this would be to simply connect the fluid lines.However, in the exemplary embodiment, the three cassette exemplary fluidflow-path schematics are combined into a cassette device which makes thesystem more compact and also, there are benefits with respect tomanufacture.

In an exemplary embodiment of this the cassette system integrated, thethree cassettes are combined in an efficient, stand alone, cassettesystem. The fluid flow-path schematics shown and described above withrespect to the various individual cassettes are combined. Thus, in somecases, fluid lines bay be in two different cassettes to save space orefficiency, but in fact, the fluid lines follow many of the same pathsas shown in the schematics.

Referring now to FIGS. 53A-53B, the mixing cassette of the cassettesystem is shown. Referring to FIGS. 54A-54B, the middle cassette for thecassette system is shown. Finally, referring to FIGS. 55A-55B, thebalancing cassette for the cassette system is shown.

Referring now to FIG. 56A, the assembled cassette system integrated isshown. The mixing cassette 500, middle cassette 600 and balancingcassette 700 are linked by fluid lines. The pods are between thecassettes. Referring now to FIGS. 56B and 56C, the various views showthe efficiency the cassette system integrated. The fluid lines 1200,1300, 1400 are shown in FIG. 60, FIG. 61 and FIG. 62 respectively. Thefluid flows between the cassette through these lines. Referring now toFIGS. 60 and 61, these fluid lines represent larger 1300, and smaller1200 check valve fluid lines. In the exemplary embodiment, the checkvalves are duck hill valves, however, in other embodiments, any checkvalve may be used. Referring to FIG. 62, fluid line 1400 is a fluid linethat does not contain a check valve.

Referring now to FIGS. 56D and 56E, the various pods 502, 504, 506, 602,604, 702, 704, 706, 708 are shown. Each of the pod housing areconstricted identically, however, the inside of the pod housing isdifferent depending on whether the pod is a pod pump 502, 504 602, 604,702, 704 a balancing chamber pods 706, 708 or a mixing chamber pod 504.

Referring now to FIGS. 57A-57C, the exemplary embodiment of the pod isshown. The pod includes two fluid ports 902, 904 (an inlet and anoutlet) and the pod may be constructed differently in the variousembodiments. A variety of embodiments of construction are described inpending U.S. patent application Ser. No. 11/787,212, filed Apr. 13, 2007and entitled Fluid Pumping Systems, Devices and Methods (E78), which ishereby incorporated herein by reference in its entirety.

Referring now to FIGS. 57A, 57D, and 57E the groove 906 in the chamberis shown. A groove 9306 is included on each half of the pod housing. nother embodiments, a groove is not included and in some embodiments, agroove is only included in one half of the pod.

Referring now to FIGS. 58A and 58B, the exemplary embodiment of themembrane used in the pod pumps 502, 504 602, 604, 702, 704 is shown.This membrane is shown and described above with respect to FIG. 5A. Inother embodiments, any of the membranes shown in FIGS. 5B-5D may beused. An exploded view of a pod pump according to the exemplaryembodiment is shown FIG. 59.

The membrane used in the balancing chamber pods 706, 708 in thepreferred embodiments is shown and described above with respect to FIGS.6A-6G. The mixing chamber pod 504 does not include a membrane in theexemplary embodiment. However, in the exemplary embodiment, the mixingchamber pod 504 includes a o-ring to seal the mixing chamber.

In the exemplary embodiment, the membrane valve membrane is shown inFIG. 2E, however, alternate embodiments as shown in FIGS. 2F and 2G mayalso be used. The metering pumps, in the exemplary embodiment, may useany of the membranes shown in FIGS. 5E-5H.

While the principles of the invention have been described herein, it isto be understood by those skilled in the art that this description ismade only by way of example and not as a limitation as to the scope ofthe invention. Other embodiments are contemplated within the scope ofthe present invention in addition to the exemplary embodiments shown anddescribed herein. Modifications and substitutions by one of ordinaryskill in the art are considered to be within the scope of the presentinvention.

1.-6. (canceled)
 7. A cassette assembly comprising a first, second andthird cassette, each said cassette comprising one or more pneumaticallyactuated diaphragm pumps or diaphragm valves, the second cassette beinginterposed between the first and third cassettes, and said first, secondand third cassettes being fluidly interconnected by a plurality of rigidconduits; wherein one or more the plurality of rigid conduits areconfigured: to carry fluid between a fluid flowpath of the firstcassette and a first fluid flowpath of the middle cassette, and to carryfluid between a fluid flowpath of the third cassette and a second fluidflowpath of the middle cassette, and to hold the first and thirdcassettes at fixed spaces from the second cassette.
 8. The cassetteassembly of claim 7, wherein at least one of the one or more of theplurality of rigid conduits includes a check valve to ensureunidirectional fluid flow.
 9. The cassette assembly of claim 7, whereinthe first and third cassettes are held against the second cassettethrough the rigid conduits by a plurality of clamps.
 10. The cassetteassembly of claim 7, wherein the first cassette and second cassettedefine a first fixed space of the fixed spaces, and the third and secondcassette define a second fixed space of the fixed spaces, and said firstand second fixed spaces are occupied by a plurality of pods, each saidpod having a rigid fluid connection to the first cassette and a separaterigid fluid connection to the second cassette if located in the firstfixed space, or having a rigid fluid connection to the third cassetteand a separate rigid fluid connection to the second cassette if locatedin the second fixed space.
 11. The cassette assembly of claim 10,wherein at least one of the plurality of pods is a diaphragm based podpump, and wherein a first rigid fluid connection of the pod pump isconfigured to carry pneumatic pressure to actuate the pod pump, and asecond rigid fluid connection of the pod pump is configured to carryfluid pumped by the pod pump.
 12. The cassette assembly of claim 10,wherein at least one of the plurality of pods is a fluid balancing podcomprising a diaphragm separating two variable fluid chambers, andwherein a first rigid fluid connection of the balancing pod isconfigured to carry a first fluid between a first variable chamber ofthe balancing pod and the second cassette, and a second rigid fluidconnection of the balancing pod is configured to carry a second fluidbetween a second variable chamber of the balancing pod and the firstcassette or the third cassette.
 13. The cassette assembly of claim 10,wherein at least one of the plurality of pods is a mixing pod comprisinga single fluid chamber, and wherein a first rigid connection of themixing pod is configured to carry a fluid between the single fluidchamber and the second cassette, and a second rigid connection of themixing pod is configured to carry the fluid between the single fluidchamber and the first cassette or the third cassette.